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  • Contrasting bacterial and archaeal distributions reflecting different geochemical processes in a sediment core from the Pearl River Estuary
    AMB Express (IF 2.226) Pub Date : 2020-01-22
    Wenxiu Wang, Jianchang Tao, Haodong Liu, Penghui Li, Songze Chen, Peng Wang, Chuanlun Zhang

    Abstract Microbial community structure and metabolic activities have profound impacts on biogeochemical processes in marine sediments. Functional bacteria such as nitrate- and sulfate-reducing bacteria respond to redox gradients by coupling specific reactions amenable to relevant energy metabolisms. However, similar functional patterns have not been observed for sedimentary archaea (except for anaerobic methanotrophs and methanogens). We coupled taxonomic composition with comprehensive geochemical species to investigate the participation of distinct bacteria and archaea in sedimentary geochemical cycles in a sediment core (300 cm) from Pearl River Estuary (PRE). Geochemical properties (NO3−, dissolved Mn and Fe, SO42+, NH4+; dissolved inorganic carbon (DIC), δ13CDIC, dissolved organic carbon (DOC), total organic carbon (TOC), δ13CTOC, and fluorescent dissolved organic matter (FDOM)) exhibited strong depth variability of different trends. Bacterial 16S rRNA- and dsrB gene abundance decreased sharply with depth while archaeal and bathyarchaeotal 16S rRNA gene copies were relatively constant. This resulted in an increase in relative abundance of archaea from surface (11.6%) to bottom (42.8%). Network analysis showed that bacterial groups of Desulfobacterales, Syntrophobacterales and Gammaproteobacteria were significantly (P < 0.0001) associated with SO42− and dissolved Mn while archaeal groups of Bathyarchaeota, Group C3 and Marine Benthic Group D (MBGD) showed close positive correlations (P < 0.0001) with NH4+, δ13CTOC values and humic-like FDOM. Our study suggested that these bacterial groups dominated in redox processes relevant to sulfate or metal oxides, while the archaeal groups are more like to degrade recalcitrant organic compounds in anaerobic sediments.

    更新日期:2020-01-23
  • Mangiferin suppresses human metastatic osteosarcoma cell growth by down-regulating the expression of metalloproteinases-1/2 and parathyroid hormone receptor 1
    AMB Express (IF 2.226) Pub Date : 2020-01-18
    Jifeng Wen, Yong Qin, Chao Li, Xiankui Dai, Tong Wu, Wenzhe Yin

    Abstract The study evaluates the protective effect of mangiferin on osteosarcoma cell proliferation and metastasis. Saos-2 and U2OS cells were treated with mangiferin (25, 50, 75 and 100 µM) for 72 h. Mangiferin reduced the cell viability, invasion, and cell adhesion and migration rate. Matrix metalloproteinases-2/9 (MMP-2/9) mRNA expression was reduced significantly, while the levels of tissue inhibitors of metalloproteinases-1/2 (TIMP-1/2) were elevated in Saos-2 and U2OS cells. Mangiferin treatment significantly reduced parathyroid hormone receptor 1 (PTHR1) mRNA and protein expression by more than 0.5-fold in both osteosarcoma cells. In addition, the immunofluorescent analysis also showed decreased PTHR1 expression following treatment with mangiferin. In summary, we have demonstrated that treatment with mangiferin reduces cell viability, proliferation, invasion, adhesion and migration, and induces apoptosis of osteosarcoma cells. Therefore, treatment with mangiferin can be effective agent in inhibiting growth and inducing apoptosis in osteosarcoma cells. Our experimental results provide evidence for the therapeutic effect of mangiferin in osteosarcoma cells.

    更新日期:2020-01-21
  • Evaluation of waste paper for cultivation of oyster mushroom ( Pleurotus ostreatus ) with some added supplementary materials
    AMB Express (IF 2.226) Pub Date : 2020-01-18
    Teklemichael Tesfay, Tesfay Godifey, Roman Mesfin, Girmay Kalayu

    Abstract Mushroom cultivation is an economically feasible bio-technological process for conversion of various lignocellulosic wastes. The aim of this study was to evaluate the suitability of waste paper supplemented with corn stalk and wheat bran for oyster mushroom cultivation. Pure culture of Oyster mushroom (Pleurotus ostreatus (Jacq.: Fr.) Kummer) was purchased from YB Plant Micropropagation Plc; Mekelle, Ethiopia. Then, the pure culture was used as inoculum for spawn preparation using sorghum prepared in Microbiology laboratory, Department of Biology, Aksum University. Waste paper supplemented with corn stalk and wheat bran with 0%, 25% and 50% were prepared. The substrates were mixed with the spawn that has been inoculated with pure culture of oyster mushroom aseptically for their productivity and biological efficiency (BE) for cultivation of P. ostreatus mushroom. Data were analyzed using SPSS version 20. Higher (26.20 ± 19.36) mean weight, pileus diameter (7.90 ± 2.66 cm), total yield (646.4 ± 273.1 g) and BE (64.64 ± 273%) were obtained from waste paper (50%) supplemented with cornstalk (25%) and wheat bran (25%). And lower (17.92 ± 81.95%) BE were obtained from waste paper (100%). Moreover, the highest (3.88 ± 0.32 cm) mean stalk length was obtained from waste paper (50%) supplemented with corn stalk (50%). This study revealed that waste paper supplemented with corn stalk and wheat bran resulted in high BE and total yield. Thus, utilization of waste paper appears to be a promising alternative for the cultivation of oyster mushroom when supplemented with other substrates.

    更新日期:2020-01-21
  • Transcriptomic profiling sheds light on the blue-light and red-light response of oyster mushroom ( Pleurotus ostreatus )
    AMB Express (IF 2.226) Pub Date : 2020-01-18
    Huan Wang, Xidan Tong, Fenghua Tian, Chuanwen Jia, Changtian Li, Yu Li

    Abstract Blue light is an important environmental factor that induces mushroom primordium differentiation and fruiting body development. Although blue-light treatment has been applied for the production of oyster mushroom (Pleurotus ostreatus), the blue-light response mechanisms of P. ostreatus still remain unclear. In the present study, we exposed the primordium of P. ostreatus to blue-light, red-light, and dark conditions for 7 days. Subsequently, comparative transcriptomics analysis of the stipe, pileus, and gill under the three light conditions was performed to reveal the gene expression response mechanism of P. ostreatus to blue light and red light. The results showed that blue light enhanced the growth and development of all the three organs of P. ostreatus, especially the pileus. In contrast, red light slightly (non-significantly) inhibited pileus growth. When compared with red-light and dark treatments, blue-light treatment significantly upregulated gene expression involved in glycolysis/gluconeogenesis, the pentose phosphate pathway and the peroxisome in the pileus, but not in the gill or stipe. Most of the glycolysis and pentose phosphate pathway genes were upregulated in the pileus by blue light. When compared with dark treatment, red-light treatment downregulated the expression of many respiration metabolism genes in the pileus. These results revealed that blue light enhanced the activation of glycolysis and the pentose phosphate pathway, whereas red light weakened glycolysis and pentose phosphate pathway activation. The conclusion can be drawn that blue light improved P. ostreatus fruiting body (particularly, the pileus) growth rate via enhancement of glycolysis and the pentose phosphate pathway.

    更新日期:2020-01-21
  • Enhancement of pullulanase production from recombinant Bacillus subtilis by optimization of feeding strategy and fermentation conditions
    AMB Express (IF 2.226) Pub Date : 2020-01-18
    Yu Zhang, Yao Nie, Xia Zhou, Jiahua Bi, Yan Xu

    Abstract Pullulanase is an important starch-debranching enzyme mostly used in starch processing-related food industries. However, the levels of pullulanase produced from recombinant Bacillus subtilis, a Generally Recognized as Safe (GRAS) host, are generally limited. To enhance the activity of pullulanase, batch fermentation and fed-batch fermentation were systematically investigated. The overall purpose is to improve the fermentation yield by optimizing the feeding strategy in the fermentation process, thereby increasing the enzyme activity of pullulanase. Therefore, in this study, the feeding methods, the feeding ingredients, the feeding concentration, and pH values were studied in detail. The optimized fermentation conditions for pullulanase production from recombinant B. subtilis were determined as following: inoculum volume 7%, pH 6.5, the dissolved oxygen level 30%, and constant-rate feeding of 100 mL glucose solution (400 g L−1) in late logarithmic growth. The OD600 of recombinant B. subtilis and enzyme activity were 84.54 and 102.75 U mL−1, which were respectively 141% and 144% higher than that before optimization. These findings provided a prerequisite for further amplification of the fermentation system to obtain higher enzyme activity.

    更新日期:2020-01-21
  • Heat shock protein 70 (HmHsp70) from Hypsizygus marmoreus confers thermotolerance to tobacco
    AMB Express (IF 2.226) Pub Date : 2020-01-18
    Lili Xu, Jie Gao, Lizhong Guo, Hao Yu

    Abstract The 70-kD heat shock proteins (Hsp70s) have been proved to be important for stress tolerance and protein folding and unfolding in almost all organisms. However, the functions of Hsp70s in mushroom are not well understood. In the present study, a hsp70 gene from Hypsizygus marmoreus, hmhsp70, was cloned and transferred to tobacco (Nicotiana tabacum) to evaluate its function in thermotolerance. Sequence alignments and phylogenetic analysis revealed that HmHsp70 may be located in the mitochondria region. qPCR analysis revealed that the transcription level of hmhsp70 in H. marmoreus mycelia increased after heat shock treatment in high temperature (42 °C) compared with untreated mycelia (at 25 °C). Transgenic tobaccos expressing hmhsp70 gene showed enhanced resistance to lethal temperature compared with the wild type (WT) plants. Nearly 30% of the transgenic tobaccos survived after treated at a high temperature (50 °C and 52 °C for 4 h); however, almost all the WT tobaccos died after treated at 50 °C and no WT tobacco survived after heat shock at 52 °C. This study firstly showed the function of a hsp70 gene from H. marmoreus.

    更新日期:2020-01-21
  • NADPH biosensor-based identification of an alcohol dehydrogenase variant with improved catalytic properties caused by a single charge reversal at the protein surface
    AMB Express (IF 2.226) Pub Date : 2020-01-18
    Alina Spielmann, Yannik Brack, Hugo van Beek, Lion Flachbart, Lea Sundermeyer, Meike Baumgart, Michael Bott

    Abstract Alcohol dehydrogenases (ADHs) are used in reductive biotransformations for the production of valuable chiral alcohols. In this study, we used a high-throughput screening approach based on the NADPH biosensor pSenSox and fluorescence-activated cell sorting (FACS) to search for variants of the NADPH-dependent ADH of Lactobacillus brevis (LbADH) with improved activity for the reduction of 2,5-hexanedione to (2R,5R)-hexanediol. In a library of approx. 1.4 × 106 clones created by random mutagenesis we identified the variant LbADHK71E. Kinetic analysis of the purified enzyme revealed that LbADHK71E had a ~ 16% lowered KM value and a 17% higher Vmax for 2,5-hexanedione compared to the wild-type LbADH. Higher activities were also observed for the alternative substrates acetophenone, acetylpyridine, 2-hexanone, 4-hydroxy-2-butanone, and methyl acetoacetate. K71 is solvent-exposed on the surface of LbADH and not located within or close to the active site. Therefore, K71 is not an obvious target for rational protein engineering. The study demonstrates that high-throughput screening using the NADPH biosensor pSenSox represents a powerful method to find unexpected beneficial mutations in NADPH-dependent alcohol dehydrogenases that can be favorable in industrial biotransformations.

    更新日期:2020-01-21
  • Recombinant expression and biochemical characterization of a novel keratinase BsKER71 from feather degrading bacterium Bacillus subtilis S1-4
    AMB Express (IF 2.226) Pub Date : 2020-01-15
    Bin Yong, Xueting Fei, Huanhuan Shao, Pan Xu, Youwen Hu, Weimin Ni, Qiuju Xiao, Xiang Tao, Xinyi He, Hong Feng

    Bacillus subtilis S1-4, isolated from chicken feather could efficiently degrade feathers by secreting several extracellular proteases. In order to get insight into the individual protease involved in keratin hydrolysis, a keratinase designed as BsKER71 was cloned and expressed in Bacillus subtilis WB600. In silico analysis revealed that BsKER71 protein contained a mature protein of 36.1 kDa. Further, purified BsKER71 could hydrolyze a variety of natural proteins, such as fibrous protein, collagen protein, casein, keratin and bovine serum albumin. In addition, this keratinase exhibited high enzyme activity in a wide range of pH and optimal pH of 10.0 and 9.0 in the hydrolysis of casein and keratin, respectively. Similarly, the optimal temperature was 55 °C and 50 °C for the hydrolysis of above two substrates, respectively. The hydrolytic activity was significantly inhibited by phenylmethanesulfonyl fluoride (PMSF), indicating the presence of serine residue in the active site. Moreover, ethylenediaminetetraacetic acid (EDTA) and phenanthroline moderately inhibited the hydrolytic activity. The catalytic activity was stimulated by Mg2+ and Ca2+, but greatly inhibited by Cu2+. Furthermore, several chemicals exhibited different effects on the hydrolysis of casein and keratin by BsKER71. These results provided a better understanding of BsKER71 from feather degrading bacterium B. subtilis S1-4.

    更新日期:2020-01-15
  • A novel trehalosamine isolated from Bacillus amyloliquefaciens and its antibacterial activities
    AMB Express (IF 2.226) Pub Date : 2020-01-14
    Ying Wang, Bo Zhao, Yaping Liu, Linjing Mao, Xuanming Zhang, Wu Meng, Kechun Liu, Jie Chu

    Abstract Bacillus amyloliquefaciens has been widely used as a probiotic in the field of biological control,and its antibacterial compounds plays an important role in the prevention and control of plant, livestock and poultry diseases. It has the advantages of green, safe and efficiency. This study aims to separate and purify active ingredient from Bacillus amyloliquefaciens GN59 and study its antibacterial activity. A novel compound was isolated from GN59 by column chromatography on silica gel and HPLC purification. The chemical structure was identified as α-d-glucopyranosyl-(1 → 1′)-3′-amino-3′-deoxy-β-d-glucopyranoside (a,β-3-trehalosamine) on the basis of spectroscopic analysis. This is the first report about a,β-3-trehalosamine isolated from biological resources on an antibiotic activity against pathogenic bacterium. The 3′-neotrehalosamine displayed antibacterial activity across a broad spectrum of microorganisms, including different gram-positive and gram-negative bacteria, with minimal inhibitory concentration (MIC) values ranging from 0.5 to 0.7 mg/mL. The results indicated that the 3′-neotrehalosamine from GN59 might be a potential candidate for bactericide.

    更新日期:2020-01-14
  • A comparison of biofiltration performance based on bacteria and fungi for treating toluene vapors from airflow
    AMB Express (IF 2.226) Pub Date : 2020-01-14
    Roohollah Ghasemi, Farideh Golbabaei, Sasan Rezaei, Mohammad Reza Pourmand, Ramin Nabizadeh, Mohammad Javad Jafari, Ensieh masoorian

    Abstract With increasing concerns about industrial gas contaminants and the growing demand for durable and sustainable technologies, attentions have been gradually shifted to biological air pollution controls. The ability of Pseudomonas putida PTCC 1694 (bacteria) and Pleurotus ostreatus IRAN 1781C (fungus) to treat contaminated gas stream with toluene and its biological degradation was compared under similar operating conditions. For this purpose, a biofilter on the laboratory scale was designed and constructed and the tests were carried out in two stages. The first stage, bacterial testing, lasted 20 days and the second stage, fungal testing, lasted 16 days. Inlet loading rates (IL) for bacterial and fungal biofilters were 21.62 ± 6.04 and 26.24 ± 7.35 g/m3 h respectively. In general, fungal biofilter showed a higher elimination capacity (EC) than bacterial biofilter (18.1 ± 6.98 vs 13.7 ± 4.7 g/m3 h). However, the pressure drop in the fungal biofilter was higher than the bacterial biofilter (1.26 ± 0.3 vs 1 ± 0.3 mm water), which was probably due to the growth of the mycelium. Fungal biofiltration showed a better performance in the removal of toluene from the air stream.

    更新日期:2020-01-14
  • Gut microbiota of red swamp crayfish Procambarus clarkii in integrated crayfish-rice cultivation model
    AMB Express (IF 2.226) Pub Date : 2020-01-14
    Yan Shui, Zheng-Bing Guan, Guo-Feng Liu, Li-Min Fan

    Abstract Increasing evidences suggest that intestinal microbiota balance closely correlated with host’s health status could affected by external environment. Integrated crayfish-rice cultivation model is a highly efficient artificial ecosystem widely practiced in subtropical China. Less information is available to estimate the influence response to the micro-ecology of crayfish intestine and so as to influence the biological processes. Thus, 16S rRNA high-throughput sequencing approach was employed to investigate the composition diversity and functions of bacterial community in the intestines of Procambarus clarkii farmed within this model. Results exhibited the highly diversity of microflora with dominant phyla Actinobacteria, Proteobacteria, Tenericutes, Firmicutes and Bacteroidetes. The genera of Candidatus Bacilloplasma and Ornithinibacter were presented as predominant population much exceeds in richness comparing to that of other genus. Despite the highly diversity in the bacterial community, the predicted functions indicated relative consistent in biological processing pathway. Collectively, significant richness of genes was observed involved in amino acid and carbohydrate metabolism and membrane transport processing. This study would contribute to the understanding of the impact of growth conditions on host–microbiota relation especially in aquatic animals.

    更新日期:2020-01-14
  • Oligotrophic bacterium Hymenobacter latericoloratus CGMCC 16346 degrades the neonicotinoid imidacloprid in surface water
    AMB Express (IF 2.226) Pub Date : 2020-01-14
    Leilei Guo, Zhiling Dai, Jingjing Guo, Wenlong Yang, Feng Ge, Yijun Dai

    Abstract The intensive and extensive application of imidacloprid in agriculture has resulted in water pollution and risks to aquatic invertebrates. However, pure bacteria remediation of imidacloprid in surface water environments has not been studied. Here, we isolated an imidacloprid-degrading bacterium from a water environment, examined its imidacloprid degradation in pure culture and surface water, sequenced its genome, and compared its Clusters of Orthologous Groups (COG) protein categorization with that for another imidacloprid-degrading bacterium. The isolate was an obligate oligotrophic bacterium, Hymenobacter latericoloratus CGMCC 16346, which degraded imidacloprid via hydroxylation by co-metabolism in pure culture. Resting cells degraded 64.4% of 100 mg/L imidacloprid in 6 days in the presence of co-substrate maltose, and growing culture degraded 40.8% of imidacloprid in 10 days. H. latericoloratus CGMCC 16346 degraded imidacloprid in surface water without co-substrate supplementation and retained imidacloprid-degrading activity after 30 days. The half-life of imidacloprid in surface water was decreased from 173.3 days in the control to 57.8 days by CGMCC 16346 inoculation. Genome sequencing and COG analysis indicated that carbohydrate metabolism and transport, cell wall/membrane biogenesis, and defense mechanisms are enriched in H. latericoloratus CGMCC 16346 compared with the copiotrophic imidacloprid-degrading Pseudoxanthomonas indica CGMCC 6648, indicating that H. latericoloratus CGMCC 16346 is adapted to live in oligotrophic water environments and biofilms. H. latericoloratus CGMCC 16346 is a promising bioremediation agent for elimination of imidacloprid contamination from surface water.

    更新日期:2020-01-14
  • Optimization and scale-up production of Zika virus ΔNS1 in Escherichia coli : application of Response Surface Methodology
    AMB Express (IF 2.226) Pub Date : 2019-12-31
    Alex Issamu Kanno, Luciana Cezar de Cerqueira Leite, Lennon Ramos Pereira, Mônica Josiane Rodrigues de Jesus, Robert Andreata-Santos, Rúbens Prince dos Santos Alves, Edison Luiz Durigon, Luís Carlos de Souza Ferreira, Viviane Maimoni Gonçalves

    Abstract Diagnosing Zika virus (ZIKV) infections has been challenging due to the cross-reactivity of induced antibodies with other flavivirus. The concomitant occurrence of ZIKV and Dengue virus (DENV) in endemic regions requires diagnostic tools with the ability to distinguish these two viral infections. Recent studies demonstrated that immunoassays using the C-terminal fragment of ZIKV NS1 antigen (ΔNS1) can be used to discriminate ZIKV from DENV infections. In order to be used in serological tests, the expression/solubility of ΔNS1 and growth of recombinant E. coli strain were optimized by Response Surface Methodology. Temperature, time and IPTG concentration were evaluated. According to the model, the best condition determined in small scale cultures was 21 °C for 20 h with 0.7 mM of IPTG, which predicted 7.5 g/L of biomass and 962 mg/L of ΔNS1. These conditions were validated and used in a 6-L batch in the bioreactor, which produced 6.4 g/L of biomass and 500 mg/L of ΔNS1 in 12 h of induction. The serological ELISA test performed with purified ΔNS1 showed low cross-reactivity with antibodies from DENV-infected human subjects. Denaturation of ΔNS1 decreased the detection of anti-ZIKV antibodies, thus indicating the contribution of conformational epitopes and confirming the importance of properly folded ΔNS1 for the specificity of the serological analyses. Obtaining high yields of soluble ΔNS1 supports the viability of an effective serologic diagnostic test capable of differentiating ZIKV from other flavivirus infections.

    更新日期:2019-12-31
  • Specific enrichment of microbes and increased ruminal propionate production: the potential mechanism underlying the high energy efficiency of Holstein heifers fed steam-flaked corn
    AMB Express (IF 2.226) Pub Date : 2019-12-28
    Hao Ren, Xiaodong Su, Hanxun Bai, Yuntian Yang, Hongrong Wang, Zeng Dan, Jinbin Lu, Shengru Wu, Chuanjiang Cai, Yangchun Cao, Xinjian Lei, Junhu Yao

    Corn grain has a high starch content and is used as main energy source in ruminant diets. Compared with finely ground corn (FGC), steam-flaked corn (SFC) could improve the milk yield of lactating dairy cows and the growth performance of feedlot cattle, but the detailed mechanisms underlying those finding are unknown. The rumen microbiome breaks down feedstuffs into energy substrates for the host animals, and contributes to feed efficiency. Therefore, the current study was conducted to investigate the ruminal bacterial community changes of heifers fed differently processed corn (SFC or FGC) using 16S rRNA sequencing technologies, and to uncover the detailed mechanisms underlying the high performance of ruminants fed the SFC diet. The results revealed that different processing methods changed the rumen characteristics and impacted the composition of the rumen bacteria. The SFC diet resulted in an increased average daily gain in heifers, an increased rumen propionate concentration and a decreased rumen ammonia nitrogen concentration. The relative abundance of the phylum Firmicutes and Proteobacteria were tended to increase or significantly increased in the heifers fed SFC diet compared with FGC diet. In addition, the relative abundance of amylolytic bacteria of the genera Succinivibrio, Roseburia and Blautia were elevated, and the cellulolytic bacteria (Ruminococcaceae_UCG-014 and Ruminococcaceae_UCG-013) were decreased by the steam flaking method. Spearman correlation analysis between the ruminal bacteria and the microbial metabolites showed that the rumen propionate concentration was positively correlated with genera Succinivibrio and Blautia abundance, but negatively correlated with genera Ruminococcaceae_UCG-014 abundance. Evident patterns of efficient improvement in rumen propionate and changes in rumen microbes to further improve feed conversion were identified. This observation uncovers the potential mechanisms underlying the increased efficiency of the SFC processing method for enhancing ruminant performance.

    更新日期:2019-12-30
  • Serotype distribution, antimicrobial susceptibility, antimicrobial resistance genes and virulence genes of Salmonella isolated from a pig slaughterhouse in Yangzhou, China
    AMB Express (IF 2.226) Pub Date : 2019-12-28
    Quan Li, Jian Yin, Zheng Li, Zewei Li, Yuanzhao Du, Weiwei Guo, Matthew Bellefleur, Shifeng Wang, Huoying Shi

    Salmonella is an important food-borne pathogen associated with public health and high economic losses. To investigate the prevalence and the characteristics of Salmonella in a pig slaughterhouse in Yangzhou, a total of 80 Salmonella isolates were isolated from 459 (17.43%) samples in 2016–2017. S. Derby (35/80, 43.75%) was the most prevalent, followed by S. Rissen (16/80, 20.00%) and S. Newlands (11/80, 13.75%). The highest rates of susceptibility were observed to cefoxitin (80/80, 100.0%) and amikacin (80/80, 100.0%), followed by aztreonam (79/80, 98.75%) and nitrofurantoin (79/80, 98.75%). The highest resistance rate was detected for tetracycline (65/80, 81.25%), followed by ampicillin (60/80, 75.00%), bactrim (55/80, 68.75%), and sulfisoxazole (54/80, 67.50%). Overall, 91.25% (73/80) of the isolates were resistant to at least one antibiotic, while 71.25% (57/80) of the isolate strains were multidrug resistant in the antimicrobial susceptibility tested. In addition, 86.36% (19/22) of the 22 antimicrobial resistance genes in the isolates were identified. Our data indicated that the resistance to certain antimicrobials was significantly associated, in part, with antimicrobial resistance genes. Furthermore, 81.25% (65/80) isolates harbored the virulence gene of mogA, of which 2 Salmonella Typhimurium isolates carried the mogA, spvB and spvC virulence genes at the same time. The results showed that swine products in the slaughterhouse were contaminated with multidrug resistant Salmonella commonly, especially some isolates carry the spv virulence genes. The virulence genes might facilitate the dissemination of the resistance genes to consumers along the production chain, suggesting the importance of controlling Salmonella during slaughter for public health.

    更新日期:2019-12-30
  • Extraction of bioactive compounds from Psidium guajava and their application in dentistry
    AMB Express (IF 2.226) Pub Date : 2019-12-28
    Shaik Shaheena, Anjani Devi Chintagunta, Vijaya Ramu Dirisala, N. S. Sampath Kumar

    Abstract Guava is considered as poor man’s apple rich in phytochemicals with medicinal value and hence it is highly consumed. Gas chromatography–mass spectroscopy (GC–MS) analysis of guava leaf extract revealed the presence of various bioactive compounds with antimicrobial, antioxidant, anticancer, and antitumor properties. Hence, it is used in tooth paste formulations along with other ingredients such as Acacia arabica gum powder, stevia herb powder, sea salt, extra virgin coconut oil, peppermint oil in the present study. Three formulations F1, F2 and F3 have been made by varying the concentration of these ingredients and the prepared formulations were studied for their antimicrobial activity and physico-chemical parameters such as pH, abrasiveness, foaming activity, spreading and cleaning ability. Among these, F3 showed significant antioxidant and antimicrobial properties, minimal cytotoxicity, maximum spreadability and very high cleaning ability. This study surmises that the herbal toothpaste formulation is greener, rich in medicinal values and imparts oral hygiene.

    更新日期:2019-12-30
  • Myricitrin exhibits anti-atherosclerotic and anti-hyperlipidemic effects in diet-induced hypercholesterolemic rats
    AMB Express (IF 2.226) Pub Date : 2019-12-21
    Jing Gao, Cuicui Liu, Heping Zhang, Zhen Sun, Rongmei Wang

    Abstract The present study investigated the anti-atherosclerotic potential of myricitrin in hypercholesterolemic rats. Rats were divided into the following groups: sham (standard food), control [1% high-cholesterol diet (HCD)], 1 μM myricitrin + 1% HCD, 10 μM myricitrin + 1% HCD, 100 μM myricitrin + 1% HCD, and the positive control (10 mg/kg body weight atorvastatin). The dose was given to rats via oral gavage for 45 consecutive days. Feeding of rats with 1% HCD caused substantial increases in the levels of LDL, cholesterol, and triglycerides (TG), while high-density lipoprotein (HDL) was reduced. However, rats supplemented with myricitrin had reduced levels of cholesterol, LDL, and TG to near-normal levels, whereas HDL was increased. Catalase, superoxide dismutase (SOD), glutathione peroxidase (Gpx), and reduced glutathione (GSH) levels were substantially reduced in the HCD-fed rats compared with sham rats. However, the rats supplemented with 100 μM myricitrin showed > 50% increases in these levels. Lipid peroxidation and reactive oxygen species (ROS) levels were reduced following myricitrin treatment. The aortic cell wall area was significantly increased by 14.5% in HCD-fed rats. However, rats supplemented with 1, 10, and 100 μM myricitrin showed significant reductions in the aortic cell wall area of 2.3%, 4%, and 27.5%, respectively. This is the first report of the anti-atherosclerotic and hypolipidemic effects of myricitrin in hypercholesterolemic rats. Myricitrin decreased the level of total serum cholesterol and the role of aortic atherosclerosis in hypercholesterolemic rats.

    更新日期:2019-12-21
  • Comparative prebiotic activity of mixtures of cereal grain polysaccharides
    AMB Express (IF 2.226) Pub Date : 2019-12-21
    Suzanne Harris, Andrea Monteagudo-Mera, Ondrej Kosik, Dimitris Charalampopoulos, Peter Shewry, Alison Lovegrove

    The main components of the non-starch polysaccharide (NSP) fraction of wheat flour are arabinoxylan (AX) and β-glucan. These are also present in other cereal grains, but their proportions vary with AX being the major component in wheat and rye and β-glucan in barley and oats. Therefore, it was hypothesised that these NSPs could act synergistically when fermented in vitro at the ratios present in the major foods consumed, resulting in increased prebiotic activity. AX and β-glucan were therefore tested in in vitro fermentation studies to assess their prebiotic activity when used individually and/or in different ratios. Short-chain fatty-acids (SCFAs) produced from in vitro fermentation were measured using HPLC and bacterial populations were measured using flow cytometry with fluorescence in situ hybridisation (Flow-FISH). Fermentation of AX alone resulted in a significant bifidogenic activity and increased concentrations of SCFAs, mainly acetate, after 8–24 h of fermentation, however β-glucan alone did not show prebiotic activity. The greatest prebiotic activity, based on concentration of total SCFAs and increases in total bacteria as well as beneficial Bifidobacterium and Clostridium coccoides/Eubacterium groups, was observed when AX and β-glucan were combined at a 3:1 ratio, which corresponds to their ratios in wheat flour which is major source of cereal fibre in the diet. This indicates that the population of bacteria in the human GI tract may be modulated by the composition of the fibre in the diet, to maximise the prebiotic potential.

    更新日期:2019-12-21
  • Beauveria bassiana for the simultaneous control of Aedes albopictus and Culex pipiens mosquito adults shows high conidia persistence and productivity
    AMB Express (IF 2.226) Pub Date : 2019-12-21
    Jin Yong Lee, Ra Mi Woo, Cheol Jun Choi, Tae Young Shin, Won Seok Gwak, Soo Dong Woo

    Abstract This study was conducted to determine the optimal entomopathogenic fungus for the simultaneous control of the adults of two mosquito species, Aedes albopictus and Culex pipiens. The pathogenicity and virulence against the two species of mosquitoes were evaluated by using 30 isolates of Beauveria bassiana, an entomopathogenic fungus isolated from Korea that has high thermotolerance and UV-B tolerance. Regarding pathogenicity, 23 isolates were pathogenic to Ae. albopictus and 12 isolates were pathogenic to Cx. pipiens; Ae. albopictus adults were more susceptible to B. bassiana than Cx. pipiens adults. Among the isolates, 6 isolates that were simultaneously pathogenic to the two species of mosquitoes were used to evaluate virulence and conidia productivity. B. bassiana CN6T1W2 and JN5R1W1 had higher virulence than the other isolates, and they were more virulent in Ae. albopictus than inCx. pipiens. The conidia productivity of B. bassiana JN5R1W1 on millet grain medium was higher than that of B. bassiana CN6T1W2. Based on these results, B. bassiana JN5R1W1 was selected as the most efficient isolate for the simultaneous control of the two mosquito species. B. bassiana JN5R1W1 can be used effectively in the development of fungal insecticides to simultaneously control Ae. albopictus and Cx. pipiens adults with similar distribution areas.

    更新日期:2019-12-21
  • Microbial inoculants: reviewing the past, discussing the present and previewing an outstanding future for the use of beneficial bacteria in agriculture
    AMB Express (IF 2.226) Pub Date : 2019-12-21
    Mariana Sanches Santos, Marco Antonio Nogueira, Mariangela Hungria

    More than one hundred years have passed since the development of the first microbial inoculant for plants. Nowadays, the use of microbial inoculants in agriculture is spread worldwide for different crops and carrying different microorganisms. In the last decades, impressive progress has been achieved in the production, commercialization and use of inoculants. Nowadays, farmers are more receptive to the use of inoculants mainly because high-quality products and multi-purpose elite strains are available at the market, improving yields at low cost in comparison to chemical fertilizers. In the context of a more sustainable agriculture, microbial inoculants also help to mitigate environmental impacts caused by agrochemicals. Challenges rely on the production of microbial inoculants for a broader range of crops, and the expansion of the inoculated area worldwide, in addition to the search for innovative microbial solutions in areas subjected to increasing episodes of environmental stresses. In this review, we explore the world market for inoculants, showing which bacteria are prominent as inoculants in different countries, and we discuss the main research strategies that might contribute to improve the use of microbial inoculants in agriculture.

    更新日期:2019-12-21
  • Effects of cobalt-histidine absorbent on aerobic denitrification by Paracoccus versutus LYM
    AMB Express (IF 2.226) Pub Date : 2019-12-17
    Chaoyue Sun, Yu Zhang, Zhenping Qu, Jiti Zhou

    To overcome the problem that ferrous complexes are easily oxidized by O2 and then lose NO binding ability in the chemical absorption-biological reduction (CABR) process, cobalt(II)-histidine [Co(II)His] was proposed as an alternative. To evaluate the applicability of Co(II)His, the effects of CoHis absorbent on the aerobic denitrification by Paracoccus versutus LYM were investigated. Results indicated that His significantly promoted nitrite reduction. The inhibition effects of CoHis absorbent could be substantially alleviated by increasing the initial His/Co2+ to 4 or higher. CoHis with concentrations of 4, 8, 12, 16 and 20 mM presented no distinct effect on nitrite reduction, but slightly inhibited the reduction of nitrate, resulting in longer lag of nitrate reduction, and obviously promoted the growth of strain LYM. In the presence of 5, 10, 15 and 20 mM CoHis absorbent, the main denitrification product was N2 (not less than 95.0%). This study is of significance in verifying the applicability of Co(II)His in the CABR process, and provides a referable CoHis absorbent concentration as 20 mM with an initial His/Co2+ of 4 for the future experiments.

    更新日期:2019-12-18
  • Recombinant polypeptide of Mycobacterium leprae as a potential tool for serological detection of leprosy
    AMB Express (IF 2.226) Pub Date : 2019-12-17
    Marcelo dos Santos Barbosa, Iara Beatriz Andrade de Sousa, Simone Simionatto, Sibele Borsuk, Silvana Beutinger Marchioro

    Current prevention methods for the transmission of Mycobacterium leprae, the causative agent of leprosy, are inadequate as suggested by the rate of new leprosy cases reported. Simple large-scale detection methods for M. leprae infection are crucial for early detection of leprosy and disease control. The present study investigates the production and seroreactivity of a recombinant polypeptide composed of various M. leprae protein epitopes. The structural and physicochemical parameters of this construction were assessed using in silico tools. Parameters like subcellular localization, presence of signal peptide, primary, secondary, and tertiary structures, and 3D model were ascertained using several bioinformatics tools. The resultant purified recombinant polypeptide, designated rMLP15, is composed of 15 peptides from six selected M. leprae proteins (ML1358, ML2055, ML0885, ML1811, ML1812, and ML1214) that induce T cell reactivity in leprosy patients from different hyperendemic regions. Using rMLP15 as the antigen, sera from 24 positive patients and 14 healthy controls were evaluated for reactivity via ELISA. ELISA-rMLP15 was able to diagnose 79.17% of leprosy patients with a specificity of 92.86%. rMLP15 was also able to detect the multibacillary and paucibacillary patients in the same proportions, a desirable addition in the leprosy diagnosis. These results summarily indicate the utility of the recombinant protein rMLP15 in the diagnosis of leprosy and the future development of a viable screening test.

    更新日期:2019-12-18
  • Phytosynthesis of BiVO 4 nanorods using Hyphaene thebaica for diverse biomedical applications
    AMB Express (IF 2.226) Pub Date : 2019-12-12
    Hamza Elsayed Ahmed Mohamed, Shakeeb Afridi, Ali Talha Khalil, Tanzeel Zohra, Muhammad Masroor Alam, Aamir Ikram, Zabta Khan Shinwari, Malik Maaza

    Biosynthesis of bismuth vanadate (BiVO4) nanorods was performed using dried fruit extracts of Hyphaene thebaica as a cost effective reducing and stabilizing agent. XRD, DRS, FTIR, zeta potential, Raman, HR-SEM, HR-TEM, EDS and SAED were used to study the main physical properties while the biological properties were established by performing diverse assays. The zeta potential is reported as − 5.21 mV. FTIR indicated Bi–O and V–O vibrations at 640 cm−1 and 700 cm−1/1120 cm−1. Characteristic Raman modes were observed at 166 cm−1, 325 cm−1 and 787 cm−1. High resolution scanning and transmission electron micrographs revealed a rod like morphology of the BiVO4. Bacillus subtilis, Klebsiella pneumonia, Fusarium solani indicated highest susceptibility to the different doses of BiVO4 nanorods. Significant protein kinase inhibition is reported for BiVO4 nanorods which suggests their potential anticancer properties. The nanorods revealed good DPPH free radical scavenging potential (48%) at 400 µg/mL while total antioxidant capacity of 59.8 µg AAE/mg was revealed at 400 µg/mL. No antiviral activity is reported on sabin like polio virus. Overall excellent biological properties are reported. We have shown that green synthesis can replace well established processes for synthesizing BiVO4 nanorods.

    更新日期:2019-12-13
  • Roles of extracellular polymeric substances in uranium immobilization by anaerobic sludge
    AMB Express (IF 2.226) Pub Date : 2019-12-11
    Hai-Ling Zhang, Meng-Xi Cheng, Shi-Cheng Li, He-Xiang Huang, Wei-Dong Liu, Xian-Jin Lyu, Jian Chu, Huan-Huan Ding, Dong Zhao, Yong-Peng Wang, Feng-Yu Huang

    The specific roles of extracellular polymeric substances (EPS) and how factors influenced EPS’s roles during U(VI) immobilization are still unclear. In this study, high content of U with the main form of nanoparticles was detected in EPS, accounting for 10–42% of total U(VI) removal. EPS might be utilized as energy source or even as electron donors when external carbon source was unavailable. The influencing degree of each experimental parameter to uranium (U) removal process was elucidated. The influential priority to U(IV)/U(VI) ratios in sludge was as follows: acetate, U(VI), and nitrate. The influential priority to total EPS contents was as follows: U(VI), nitrate and acetate. The complex interaction mechanism between U(VI) and EPS in the U immobilization process was proposed, which might involve three ways including biosorption, bioreduction and bioprecipitation. These results indicate important and various roles of EPS in U(VI) immobilization.

    更新日期:2019-12-11
  • Using submerged fermentation to fast increase N6-(2-hydroxyethyl)-adenosine, adenosine and polysaccharide productions of Cordyceps cicadae NTTU 868
    AMB Express (IF 2.226) Pub Date : 2019-12-09
    Bo-Jun Ke, Chun-Lin Lee

    Cordyceps cicadae is a well-known traditional Chinese medicine for treating palpitations and eye diseases. It contains several bioactive compounds such as adenosine, N6-(2-hydroxyethyl)-adenosine (HEA), and polysaccharide. Those bioactive compounds have been reported to perform anti-oxidation and anti-inflammatory properties and provide renal protection. In this study, we researched different fermentation conditions in order to enhance the biomass, adenosine, HEA, and polysaccharide productions of C. cicadae NTTU 868. Solid fermentation was carried out with different grain substrates (barley, oat, rice and wheat). Various submerged fermentation scales were used to produce the C. cicadae NTTU 868 mycelium. The results of solid fermentation revealed that C. cicadae NTTU 868 produced higher adenosine and HEA concentrations in oat rather than in other substrates. C. cicadae NTTU 868 mycelium had obtained the highest concentrations of adenosine and HEA on Day 2 as using the small-scale submerged fermentation. Furthermore, potato dextrose broth with extra 0.2% of yeast extract was able to result in higher HEA concentration. In conclusion, using submerged fermentation to culture C. cicadae NTTU 868 resulted in more efficient adenosine, HEA, and polysaccharide productions than using solid-fermentation, especially when 0.2% of yeast extract was used in the PDB. Importantly, this can be easily scaled-up in the fermentation industry.

    更新日期:2019-12-09
  • Development of loop-mediated isothermal amplification coupled with nanoparticle-based lateral flow biosensor assay for Mycoplasma pneumoniae detection
    AMB Express (IF 2.226) Pub Date : 2019-12-05
    Yacui Wang, Yi Wang, Weiwei Jiao, Jieqiong Li, Shuting Quan, Lin Sun, Yonghong Wang, Xue Qi, Xingyun Wang, Adong Shen

    Mycoplasma pneumoniae (MP) is one of the most common pathogens causing respiratory tract infection, especially for community-acquired pneumonia (CAP) in school-age children. There was considerable amount of studies on loop-mediated isothermal amplification (LAMP) assay for MP detection. However, the result interpretation of these developed LAMP assays was sophisticated and subjective. Therefore, we developed and evaluated a LAMP coupled with nanoparticle-based lateral flow biosensor (LFB) assay (LAMP-LFB) for simple, reliable, and objective identification of MP (MP-LAMP-LFB). Six primers specific to P1 gene of MP were designed, and the preferred temperature for this assay was confirmed to be 65 °C. The amplification products could be visually interpreted by LFB within 2 min. The MP-LAMP-LFB assay specifically identified DNA templates of MP, and no cross-reactivity with other pathogens was obtained. The limit of the detection for this assay was 600 fg of DNA templates in pure cultures, which was in complete accordance with colorimetric indicator detection and agarose gel electrophoresis analysis. This assay was applied to 209 oropharyngeal swab specimens collected from children with acute respiratory tract infection for clinical evaluation, and compared to real-time PCR detection. Using the LAMP-LFB and real-time PCR assay, the positive rates of MP were 47.8% and 31.6%, respectively. Results suggested that the LAMP-LFB assay displayed high sensitivity compared to real-time PCR method. In summary, LAMP-LFB assay established here was a simple, objective, and sensitive assay for MP detection, which can be widely applied in clinical settings, especially in rural areas.

    更新日期:2019-12-05
  • Effect of the luxI/R gene on AHL-signaling molecules and QS regulatory mechanism in Hafnia alvei H4
    AMB Express (IF 2.226) Pub Date : 2019-12-05
    Xue Li, Gongliang Zhang, Yaolei Zhu, Jingran Bi, Hongshun Hao, Hongman Hou

    Hafnia alvei H4 is a bacterium subject to regulation by a N-acyl-l-homoserine lactone (AHL)-mediated quorum sensing system and is closely related to the corruption of instant sea cucumber. Studying the effect of Hafnia alvei H4 quorum sensing regulatory genes on AHLs is necessary for the quality and preservation of instant sea cucumber. In this study, the draft genome of H. alvei H4, which comprises a single chromosome of 4,687,151 bp, was sequenced and analyzed and the types of AHLs were analyzed employing thin-layer chromatography (TLC) and high resolution triple quadrupole liquid chromatography/mass spectrometry (LC/MS). Then the wild-type strain of H. alvei H4 and the luxI/R double mutant (ΔluxIR) were compared by transcriptome sequencing (RNA-seq). The results indicate that the incomplete genome sequence revealed the presence of one quorum-sensing (QS) gene set, designated as lasI/expR. Three major AHLs, N-hexanoyl-l-homoserine lactone (C6-HSL), N-butyryl-l-homoserine lactone (C4-HSL), and N-(3-oxo-octanoyl)-l-homoserine lactone (3-oxo-C8-HSL) were found, with C6-HSL being the most abundant. C6-HSL was not detected in the culture of the luxI mutant (ΔluxI) and higher levels of C4-HSL was found in the culture of the luxR mutant (ΔluxR), which suggested that the luxR gene may have a positive effect on C4-HSL production. It was also found that AHL and QS genes are closely related in the absence of luxIR double deletion. The results of this study can further elucidate at the genetic level that luxI and luxR genes are involved in the regulation of AHL.

    更新日期:2019-12-05
  • Transient expression analysis of synthetic promoters containing F and D cis -acting elements in response to Ascochyta rabiei and two plant defense hormones
    AMB Express (IF 2.226) Pub Date : 2019-12-04
    Farhad Shokouhifar, Marjan Bahrabadi, Abdolreza Bagheri, Mojtaba Mamarabadi

    Introduction of a foreign gene coding for a pathogen resistant protein into the target plant and constitutive expression of Resistance (R) proteins may confer high level of resistance. However, genetic engineering could lead to reprogramming of molecular mechanisms that manage physiological behavior, which in turn could lead to undesired results. Therefore, using a pathogen-inducible synthetic promoter approach, response to pathogens could be more specific. Ascochyta rabiei is a destructive fungal pathogen in chickpea production. In this study, we analyzed the expression pattern of three synthetic promoters in response to pathogen and two defense hormones. We have tested three synthetic pathogen-inducible promoters designated as (1) synthetic promoter-D box-D box (SP-DD), (2) synthetic promoter-F element-F element (SP-FF) and (3) synthetic promoter-F element-F element-D box-D box (SP-FFDD) via Agrobacterium transient expression assay. The cis-acting element designated as ‘D’ is a 31 base pair sequence from the promoter of parsley pathogenesis-related gene 2 (PR2 gene) and the cis-acting element designated as ‘F’ is a 39 base pairs sequence from the promoter of Arabidopsis AtCMPG1 gene. We used mycelial extracts from two pathotypes of A. rabiei as elicitor to define the responsiveness of the promoters against pathogen. Plant phytohormones including salicylic acid and methyl jasmonate were also used to study the promoter sensitivity in plant signaling pathways. Our results showed that the SP-FF promoter was highly inducible to A. rabiei and methyl jasmonate as well, while the SP-DD promoter was more sensitive to salicylic acid. The SP-FFDD promoter was equally responsive to both pathotypes of A. rabiei which is probably due to the complex nature of box D cis-acting element.

    更新日期:2019-12-04
  • Evaluation of antiviral activity of Bacillus licheniformis -fermented products against porcine epidemic diarrhea virus
    AMB Express (IF 2.226) Pub Date : 2019-12-03
    Ju-Yi Peng, Yi-Bing Horng, Ching-Ho Wu, Chia-Yu Chang, Yen-Chen Chang, Pei-Shiue Tsai, Chian-Ren Jeng, Yeong-Hsiang Cheng, Hui-Wen Chang

    Bacillus licheniformis (B. licheniformis) is commonly used as probiotic and its secondary metabolites are attractive anti-microbial candidate. In the present study, we aimed to evaluate the antiviral activity of crude extracts from B. licheniformis against porcine epidemic diarrhea virus (PEDV), a highly contagious enveloped porcine virus that has caused great economic loss in pigs. In vivo, PEDV-infected piglets supplemented with air-dried solid state fermentative cultivate containing B. licheniformis-fermented products (BLFP) showed milder clinical symptoms and decreased viral shedding. Importantly, no significant systemic pathological lesions and no reduction in average daily gain were noted in pigs supplemented with the BLFP, which suggests that it is safe for use in pigs. In vitro experiments revealed that while B. licheniformis crude extracts exhibited no toxicity in Vero cells, co-cultivation of B. licheniformis crude extracts with PEDV significantly reduced viral infection and replication. Summarized current results suggest that the B. licheniformis-fermented products could be a novel candidate food additive for reducing the impact of PED on the swine industry.

    更新日期:2019-12-03
  • Anti-HIV, antitumor and immunomodulatory activities of paclitaxel from fermentation broth using molecular imprinting technique
    AMB Express (IF 2.226) Pub Date : 2019-12-03
    Junhyok Ryang, Yan Yan, Yangyang Song, Fang Liu, Tzi Bun Ng

    In this study, a single component paclitaxel was obtained from fermentation broth by molecular imprinting technique, and its antiviral, antitumor and immunomodulatory activities were studied. The results showed that paclitaxel had a good inhibitory activity on human breast cancer MCF-7 cells and showed a concentration- dependent relationship with an IC50 of about 15 μg/mL in the sulforhodamine B assay. At the same time, paclitaxel exerted a weak inhibitory activity on cervical cancer Hela cells. In addition, paclitaxel not only inhibited the invasion of HIV-1 pseudovirus into cells, but also exhibited inhibitory activity to a certain extent after viral invasion of the cells. At a paclitaxel concentration of 20 μg/mL, the inhibition of HIV-1 pseudovirus reached about 66%. The inhibition of HIV-1 protease activity was concentration-dependent. At a concentration of 20 μg/mL, the inhibitory effect of paclitaxel on HIV-1 protease was similar to that of the positive control pepstatin A, being 15.8%. The HIV-1 integrase inhibiting activity of paclitaxel was relatively weak. Paclitaxel significantly up-regulated the expression of interleukin-6.

    更新日期:2019-12-03
  • Identification and denitrification characteristics of a salt-tolerant denitrifying bacterium Pannonibacter phragmitetus F1
    AMB Express (IF 2.226) Pub Date : 2019-12-03
    Xinyi Wang, Hui Zhu, Brian Shutes, Baorong Fu, Baixing Yan, Xiangfei Yu, Huiyang Wen, Xin Chen

    A salt-tolerant denitrifying bacterium F1 was isolated in this study, which has high nitrite (NO2−–N) and nitrate (NO3−–N) removal abilities. The salt tolerance capacity of strain F1 was further verified and the effects of initial pH, initial NaNO2 concentration and inoculation size on the denitrification capacity of strain F1 under saline conditions were evaluated. Strain F1 was identified as Pannonibacter phragmitetus and named Pannonibacter phragmitetus F1. This strain can tolerate NaCl concentrations up to 70 g/L, and its most efficient denitrification capacity was observed at NaCl concentrations of 0–10 g/L. Under non-saline condition, the removal percentages of NO2−–N and NO3−–N by strain Pannonibacter phragmitetus F1 at pH of 10 and inoculation size of 5% were 100% and 83%, respectively, after cultivation for 5 days. Gas generation was observed during the cultivation, indicating that an efficient denitrification performance was achieved. When pH was 10 and the inoculation size was 5%, both the highest removal percentages of NO2−–N (99%) and NO3−–N (95%) by strain Pannonibacter phragmitetus F1 were observed at NaCl concentration of 10 g/L. When the NaCl concentration was 10 g/L, strain Pannonibacter phragmitetus F1 can adapt to a wide range of neutral and alkaline environments (pH of 7–10) and is highly tolerant of NaNO2 concentration (0.4–1.6 g/L). In conclusion, strain Pannonibacter phragmitetus F1 has a great potential to be applied in the treatment of saline wastewater containing high nitrogen concentrations, e.g. coastal aquaculture wastewater.

    更新日期:2019-12-03
  • The occurrence of the multidrug resistance (MDR) and the prevalence of virulence genes and QACs resistance genes in E. coli isolated from environmental and avian sources
    AMB Express (IF 2.226) Pub Date : 2019-12-03
    Mohamed E. Enany, Abdelazeem M. Algammal, Soad A. Nasef, Sara A. M. Abo-Eillil, May Bin-Jumah, Ayman E. Taha, Ahmed A. Allam

    None

    更新日期:2019-12-03
  • Arsenic metabolism in technical biogas plants: possible consequences for resident microbiota and downstream units
    AMB Express (IF 2.226) Pub Date : 2019-11-28
    Nicolas Weithmann, Stanislava Mlinar, Frank Hilbrig, Samer Bachmaf, Julia Arndt, Britta Planer-Friedrich, Alfons R. Weig, Ruth Freitag

    The metal(loid) and in particular the Arsenic (As) burden of thirteen agricultural biogas plants and two sewage sludge digesters were investigated together with the corresponding microbial consortia. The latter were characterized by ARISA (automated ribosomal intergenetic spacer analysis) and next generation sequencing. The consortia were found to cluster according to digester type rather than substrate or metal(loid) composition. For selected plants, individual As species in the liquid and gaseous phases were quantified, showing that the microorganisms actively metabolize and thereby remove the As from their environment via the formation of (methylated) volatile species. The As metabolites showed some dependency on the microbial consortia, while there was no statistical correlation with the substrate mix. Finally, slurry from one agricultural biogas plant and one sewage sludge digester was transferred into laboratory scale reactors (“satellite reactors”) and the response to a defined addition of As (30 and 60 µM sodium arsenite) was studied. The results corroborate the hypothesis of a rapid conversion of dissolved As species into volatile ones. Methanogenesis was reduced during that time, while there was no discernable toxic effect on the microbial population. However, the utilization of the produced biogas as replacement for natural gas, e.g. as fuel, may be problematic, as catalysts and machinery are known to suffer from prolonged exposure even to low As concentrations.

    更新日期:2019-11-29
  • Antibacterial activity of Bacillus species-derived surfactin on Brachyspira hyodysenteriae and Clostridium perfringens
    AMB Express (IF 2.226) Pub Date : 2019-11-21
    Yi-Bing Horng, Yu-Hsiang Yu, Andrzej Dybus, Felix Shih-Hsiang Hsiao, Yeong-Hsiang Cheng

    Swine dysentery and necrotic enteritis are a bane to animal husbandry worldwide. Some countries have already banned the use of antibiotics as growth promoters in animal production. Surfactin is a potential alternative to antibiotics and antibacterial agents. However, the antibacterial activity of Bacillus species-derived surfactin on Brachyspira hyodysenteriae and Clostridium perfringens are still poorly understood. In the current study, the antibacterial effects of surfactin produced from Bacillus subtilis and Bacillus licheniformis on B. hyodysenteriae and C. perfringens were evaluated. Results showed that multiple surfactin isoforms were detected in B. subtilis, while only one surfactin isoform was detected in B. licheniformis fermented products. The surfactin produced from B. subtilis exhibited significant antibacterial activity against B. hyodysenteriae compared with surfactin produced from B. licheniformis. B. subtilis-derived surfactin could inhibit bacterial growth and disrupt the morphology of B. hyodysenteriae. Furthermore, the surfactin produced from B. subtilis have the highest activity against C. perfringens growth. In contrast, B. licheniformis fermented product-derived surfactin had a strong bacterial killing activity against C. perfringens compared with surfactin produced from B. subtilis. These results together suggest that Bacillus species-derived surfactin have potential for development as feed additives and use as a possible substitute for antibiotics to prevent B. hyodysenteriae and C. perfringens-associated disease in the animal industry.

    更新日期:2019-11-28
  • Secreting-lux/pT-ClyA engineered bacteria suppresses tumor growth via interleukin-1β in two pathways
    AMB Express (IF 2.226) Pub Date : 2019-11-21
    Yuqin Wu, Zhicai Feng, Shengnan Jiang, Jing Chen, Yuefu Zhan, Jianqiang Chen

    Engineered Salmonella typhimurium (S.t-ΔpGlux/pT-ClyA) and attenuated Salmonella typhimurium (SL: Salmonella typhimurium with a defect in the synthesis of guanine 5′-diphosphate-3′-diphosphate) exhibit similar tumor targeting capabilities (Kim et al. in Theranostics 5:1328–1342, 2015; Jiang et al. in Mol Ther 18:635–642, 2013), but S.t-ΔpGlux/pT-ClyA exerts superior tumor suppressive effects. The aim of this study was to investigate whether S.t-ΔpGlux/pT-ClyA inhibits colon cancer growth and recurrence by promoting increased IL-1β production. The CT26 tumor mouse model was used, and mice were treated in the following ways: PBS, S.t-ΔpGlux/pT-ClyA(+) + IL-1βAb, SL, S.t-ΔpGlux/pT-ClyA(−), and S.t-ΔpGlux/pT-ClyA(+). Dynamic evaluation of the efficacy of S.t-ΔpGlux/pT-ClyA in the treatment of colon cancer was assessed by MRI. Western blot, immunofluorescence and flow cytometry analysis were used to investigate IL-1β-derived cells and IL-1β expression on tumor cells and immune cells to analyze the regulatory mechanism. IL-1β levels in tumors colonized by S.t-ΔpGlux/pT-ClyA were significantly increased and maintained at high levels compared to control treatments. This increase caused tumors to subside without recurrence. We examined the immune cells mediating S.t-ΔpGlux/pT-ClyA-induced tumor suppression and examined the major cell types producing IL-1β. We found that macrophages and dendritic cells were the primary IL-1β producers. Inhibition of IL-1β in mice treated with S.t-ΔpGlux/pT-ClyA using an IL-1β antibody caused tumor growth to resume. This suggests that IL-1β plays an important role in the treatment of cancer by S.t-ΔpGlux/pT-ClyA. We found that in St-ΔpGlux/pT-ClyA-treated tumors, expression of molecules involved in signaling pathways, such as NLRP3, ASC, Caspase1, TLR4, MyD88, NF-kB and IL-1β, were upregulated, while in ΔppGpp S. typhimurium treated animals, TLR4, MyD88, NF-kB and IL-1β were upregulated with NLRP3, ASC, and Caspase1 being rarely expressed or not expressed at all. Using S.t-ΔpGlux/pT-ClyA may simultaneously activate TLR4 and NLRP3 signaling pathways, which increase IL-1β expression and enhance inhibition of colon cancer growth without tumor recurrence. This study provides a novel platform for treating colon cancer.

    更新日期:2019-11-28
  • Comparison of the intestinal microbiota composition and function in healthy and diseased Yunlong Grouper
    AMB Express (IF 2.226) Pub Date : 2019-11-21
    Chao Ma, Chunxiu Chen, Lei Jia, Xiaoxu He, Bo Zhang

    Maintaining stabilization of the intestinal microbiota is important in preventing bacterial diseases in cultured fish. At present, there have been no reports on the composition and functional analysis of intestinal microbiota in Yunlong Grouper (Epinephelus moara♀ × Epinephelus lanceolatus♂). In this study we analyzed and compared the intestinal microbiota composition of healthy and diseased pond-reared fish to discern the functional profile of a healthy status. The richness and diversity of the intestinal microbiota did not differ significantly between diseased and healthy fish, yet the abundance of predominant phyla like the Proteobacteria were upregulated in the diseased Yunlong Grouper. At the genus level, a significant reduction of Cetobacterium was observed in the intestinal tracts of diseased fish, as Pseudomonas became the most dominant bacterium. To compare the intestinal microorganism abundances between the two health groups of fish, we first screened the gut bacteria and discerned 4 phyla and 12 genera to designate a healthy status in Yunlong Grouper. The environmental bacterial community influenced composition of the intestinal microbiota in Yunlong Grouper, and the intestinal microbiota of diseased fish was more susceptible to the influence of the culture water. In addition, the prediction of functional genes by phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) indicated that the intestinal microbiota of Yunlong Grouper is related mainly to the terms “metabolism, environmental information processing, genetic information processing, human diseases, and cellular processing; moreover, the functions of the intestinal microbiota differed between the different health states of this fish. The overall results indicate that the occurrence of disease can affect the composition and function of the intestinal microbiota in a cultured fish.

    更新日期:2019-11-28
  • Putative metabolic pathway for the bioproduction of bikaverin and intermediates thereof in the wild Fusarium oxysporum LCP531 strain
    AMB Express (IF 2.226) Pub Date : 2019-11-20
    Juliana Lebeau, Thomas Petit, Laurent Dufossé, Yanis Caro

    Fungal naphthoquinones, like red bikaverin, are of interest due to their growing applications in designing pharmaceutical products. Though considerable work has been done on the elucidation of bikaverin biosynthesis pathway in Fusarium fujikuroi, very few reports are available regarding its bioproduction in F. oxysporum. We are hereby proposing a putative metabolic pathway for bikaverin bioproduction in a wild F. oxysporum strain by cross-linking the pigment profiles we obtained under two different fermentation conditions with literature. Naphthoquinone pigments were extracted with a pressurized liquid extraction method, and characterized by HPLC–DAD and UHPLC-HRMS. The results led to the conclusions that the F. oxysporum LCP531 strain was able to produce bikaverin and its various intermediates, e.g., pre-bikaverin, oxo-pre-bikaverin, dinor-bikaverin, me-oxo-pre-bikaverin, and nor-bikaverin, in submerged cultures in various proportions. To our knowledge, this is the first report of the isolation of these five bikaverin intermediates from F. oxysporum cultures, providing us with steady clues for confirming a bikaverin metabolic pathway as well as some of its regulatory patterns in the F. oxysporum LCP531 strain, based on the previously reported model in F. fujikuroi. Interestingly, norbikaverin accumulated along with bikaverin in mycelial cells when the strain grew on simple carbon and nitrogen sources and additional cofactors. Along bikaverin production, we were able to describe the excretion of the toxin beauvericin as main extrolite exclusively in liquid medium containing complex nitrogen and carbon sources, as well as the isolation of ergosterol derivate in mycelial extracts, which have potential for pharmaceutical uses. Therefore, culture conditions were also concluded to trigger some specific biosynthetic route favoring various metabolites of interest. Such observation is of great significance for selective production of pigments and/or prevention of occurrence of others (aka mycotoxins).

    更新日期:2019-11-28
  • Development of a multiplex PCR assay for the simultaneous and rapid detection of six pathogenic bacteria in poultry
    AMB Express (IF 2.226) Pub Date : 2019-11-14
    Zhihao Wang, Jiakun Zuo, Jiansen Gong, Jiangang Hu, Wei Jiang, Rongsheng Mi, Yan Huang, Zhaoguo Chen, Vanhnaseng Phouthapane, Kezong Qi, Chen Wang, Xiangan Han

    Escherichia coli, Pasteurella multocida, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella spp. and Staphylococcus aureus are six bacterial pathogens of avian. However, these pathogens may cause many similar pathological changes, resulting in clinical isolates that are difficult to quickly and simultaneously detect and identify. Here, a multiplex polymerase chain reaction (m-PCR) assay is reported to rapidly identify targets genes (phoA, KMT1, ureR, toxA, invA, and nuc) of these six pathogens in clinical samples. Six pairs of specific primers were designed. The optimal reaction conditions, specificity, and sensitivity of the m-PCR assay were investigated. The results showed that betaine remarkably improved amplification of the target genes. Specific test results showed that all six pathogens were detected by the proposed m-PCR protocol without cross-amplification with viruses or parasites. Sensitivity test results showed that the m-PCR system could amplify the six target genes from bacterial genomes or cultures with template amounts of 500 pg or 2.8–8.6 × 103 colony forming units, respectively. Furthermore, the six bacterial pathogens isolated from the infected tissue samples were successfully identified. The proposed m-PCR assay is a useful tool to monitor and diagnose bacterial infection in birds with high specificity, sensitivity and throughput.

    更新日期:2019-11-28
  • Optimization of agro-residues as substrates for Pleurotus pulmonarius production
    AMB Express (IF 2.226) Pub Date : 2019-11-14
    Nan Wu, Fenghua Tian, Odeshnee Moodley, Bing Song, Chuanwen Jia, Jianqiang Ye, Ruina Lv, Zhi Qin, Changtian Li

    The “replacing wood by grass” project can partially resolve the conflict between mushroom production and balancing the ecosystem, while promoting agricultural economic sustainability. Pleurotus pulmonarius is an economically important edible and medicinal mushroom, which is traditionally produced using a substrate consisting of sawdust and cottonseed hulls, supplemented with wheat bran. A simplex lattice design was applied to systemically optimize the cultivation of P. pulmonarius using agro-residues as the main substrate to replace sawdust and cottonseed hulls. The effects of differing amounts of wheat straw, corn straw, and soybean straw on the variables of yield, mycelial growth rate, stipe length, pileus length, pileus width, and time to harvest were demonstrated. Results indicated that a mix of wheat straw, corn straw, and soybean straw may have significantly positive effects on each of these variables. The high yield comprehensive formula was then optimized to include 40.4% wheat straw, 20.3% corn straw, 18.3% soybean straw, combined with 20.0% wheat bran, and 1.0% light CaCO3 (C/N = 42.50). The biological efficiency was 15.2% greater than that of the control. Most encouraging was the indication that the high yield comprehensive formula may shorten the time to reach the reproductive stage by 6 days, compared with the control. Based on the results of this study, agro-residues may be used as a suitable substitution for sawdust and cottonseed hulls as the main cultivation substrates of P. pulmonarius. These results provide a theoretical basis for the “replacing wood by grass” project on edible mushroom cultivation.

    更新日期:2019-11-28
  • Resazurin assay for assessment of antimicrobial properties of electrospun nanofiber filtration membranes
    AMB Express (IF 2.226) Pub Date : 2019-11-13
    Eva Travnickova, Premysl Mikula, Jakub Oprsal, Marie Bohacova, Lubomir Kubac, Dusan Kimmer, Jana Soukupova, Michal Bittner

    We developed a simple and fast microplate assay for evaluation of the antimicrobial activity of electrospun nanofiber filtration membranes or similar porous materials for water treatment technologies. Resazurin (alamarBlue®) was used as an indicator of the amount of viable experimental microorganisms Gram-negative Escherichia coli, Gram-positive Enterococcus faecalis, and natural wastewater treatment plant effluent bacteria. A bacterial inoculum of concentration 1–3 × 105 CFU mL−1 was pipetted onto the surface of assessed both functionalized and respective control membranes and incubated in 12-well plates for 4 h at 37 °C. Kinetics of resazurin metabolization, i.e. its reduction to fluorescent resorufin, was evaluated fluorimetrically (λex520/λem590 nm). A number of viable bacteria on the membranes expressed as CFU mL−1 was calculated from the kinetic curves by using calibration curves that were constructed for both experimental bacterial species. Antimicrobial activities of the membranes were evaluated by either resazurin assay or modified ISO 20743 plate count assay. Results of both assays showed the significant antimicrobial activity of membranes functionalized with silver nanoparticles for both bacterial species and wastewater treatment plant effluent bacteria as well (log CFU reduction compared to control membrane > 4), while membranes containing specific quaternary ammonium salts were inefficient (log CFU reduction < 1). The suitability of resazurin microplate assay for testing nanofiber filtration membranes and analogous matrices has proven to be a faster and less demanding alternative to the traditionally used approach providing comparable results.

    更新日期:2019-11-28
  • Bifidogenic and butyrogenic effects of young barely leaf extract in an in vitro human colonic microbiota model
    AMB Express (IF 2.226) Pub Date : 2019-11-13
    Daisuke Sasaki, Kengo Sasaki, Yasushi Kadowaki, Yasuyuki Aotsuka, Akihiko Kondo

    Young barley leaf extract (YBL) contains beneficial substances such as fructans, minerals, and vitamins. The effects of YBL administration on the human colonic microbiota and its production of metabolites were evaluated using an in vitro model culture system. Fermentations were started by inoculating fecal samples from nine healthy subjects, with or without 1.5% YBL. Bacterial 16S rRNA sequencing results confirmed that YBL administration significantly increased the relative abundances of bacteria related to the genus Bifidobacterium (p = 0.001, paired t-test) and those of the genera Faecalibacterium, Roseburia, Unclassified Ruminococcaceae, and Lachnospira (p = 0.013, p = 0.019, p = 0.028, and p = 0.034, respectively, paired t-test). Increased abundances of the latter genera corresponded to increased butyrate production in human colonic microbiota models following fermentation with 1.5% YBL, when compared to fermentation without 1.5% YBL (p = 0.006, Dunnett’s test). In addition, YBL administration significantly increased the production levels of amino acids such as lysine, glutamate, serine, threonine, alanine, isoleucine, leucine, valine, and phenylalanine. Therefore, our results showed the health-promoting bifidogenic and butyrogenic effects of YBL.

    更新日期:2019-11-28
  • An exploration of the rapid transformation method for Dunaliella salina system
    AMB Express (IF 2.226) Pub Date : 2019-11-09
    Guannan Song, Wan Wang, Lina Hu, Yu Liu, Aifang Li, Jingxia Du, Jiao Wang, Mengyuan Jia, Shuying Feng

    As a new expression system, Dunaliella salina (D. salina) has bright prospects and applications in various fields. However, its application is currently restricted because of the low expression and instability of foreign gene in D. salina cells. During genetic operation, transformation is a crucial step for genes expression in D. salina system. Although several transformation methods are existing currently, many inherent deficiencies and limitations still can be found in actual practice. Thus, we attempted to set up a rapid transformation method using the change of salt concentrations for D. salina. Based on osmotic pressure difference, exogenous genes can be spontaneously transferred into D. salina cells. After that, transformed D. salina cells were subjected to histochemical and molecular analysis. The results showed that the reporter gene, beta-glucuronidase genes were successfully expressed in the positive transformants, and detected in all of transformed cells by PCR analysis. Moreover, different transformation parameters, containing the salt gradient, time, dye dosage and Triton X-100 concentration, were optimized to obtain an optimal transformation result. Taken together, we preliminarily established a rapid transformation method with the features of fast, simple, economic, and high-efficient. This method will provide a strong genetic manipulation tool for the future transformation of D. salina system.

    更新日期:2019-11-28
  • Silage fermentation and ruminal degradation of cassava foliage prepared with microbial additive
    AMB Express (IF 2.226) Pub Date : 2019-11-09
    Mao Li, Xuejuan Zi, Hanlin Zhou, Renlong Lv, Jun Tang, Yimin Cai

    To effectively utilize the tropical cassava (Manihot esculenta Crantz) foliage (CF) resources, the CF silages were prepared with microbial additives, including Chikuso-1 (CH1, Lactobacillus plantarum), Snow Lact L (SN, L. rhamnosus), Acremonium cellulase (CE), SN + CE and CH1 + CE. Silage fermentation, chemical composition and ruminal degradation were studied in Hainan, China. CF silages prepared with lactic acid bacteria (LAB) and CE were well preserved, with a higher (P < 0.05) lactic acid, a lower (P < 0.05) pH value, butyric acid content and NH3-N ⁄ total-N compared with the controls. The additive-treated silages showed increased crude protein (CP) content, but decreased (P < 0.05) NDF and ADF contents. Meanwhile, the additive treatment improved relative feed value and ruminal degradability of dry matter (DM), CP, neutral detergent fiber and acid detergent fiber. In addition, the combination of LAB and CE resulted in better fermentation quality and ruminal degradability compared with LAB or CE single treatment. The results demonstrated that the CF could be prepared as ruminant feed, and the combination of LAB and CE might exert beneficial synergistic effect on silage fermentation.

    更新日期:2019-11-28
  • Two-step genomic sequence comparison strategy to design Trichoderma strain-specific primers for quantitative PCR
    AMB Express (IF 2.226) Pub Date : 2019-11-09
    Yang Zhang, Xiang Wang, Guan Pang, Feng Cai, Jian Zhang, Zongzhuan Shen, Rong Li, Qirong Shen

    Survival of inoculated fungal strains in a new environment plays a critical role in functional performance, but few studies have focused on strain-specific quantitative PCR (qPCR) methods for monitoring beneficial fungi. In this study, the Trichoderma guizhouense strain NJAU 4742 (transformed with the gfp gene and named gfp-NJAU 4742), which exhibits a growth-promoting effect by means of phytohormone production and pathogen antagonism, was selected as a model to design strain-specific primer pairs using two steps of genomic sequence comparison to detect its abundance in soil. After a second comparison with the closely related species T. harzianum CBS 226-95 to further differentiate the strain-specific fragments that had shown no homology to any sequence deposited in the databases used in the first comparison, ten primer pairs were designed from the whole genome. Meanwhile, 3 primer pairs, P11, P12 and P13, were also designed from the inserted fragment containing the gfp gene. After verification testing with three types of field soils, primer pairs P6, P7 and P8 were further selected by comparison with P11, P12 and P13. A practical test using a pot experiment showed that stable colonization of gfp-NJAU 4742 in pepper rhizosphere soil could be detected using primer pairs P6 and P7, showing no significant difference from the results of primers P11 and P12. Hence, the strategy described here for designing fungal-strain-specific primers may theoretically be used for any other fungi for which the whole genome sequence is available in a database, and the qPCR methodology developed can also be used to further monitor the population dynamics of different strains based on the designed primers.

    更新日期:2019-11-28
  • Effect of bovine lactoferrin as a novel therapeutic agent in a rat model of sepsis-induced acute lung injury
    AMB Express (IF 2.226) Pub Date : 2019-10-31
    Nannan Han, Hengjie Li, Gang Li, Ye Shen, Min Fei, Yong Nan

    Sepsis is a serious clinical condition resulting from severe infection. High rates of mortality and tissue damage have been reported in intensive care unit (ICU) patients with sepsis. Bovine lactoferrin (BLF) is a well-known 80-kDa glycoprotein in the transferrin family that inhibits sepsis in low-birth-weight neonates. The present study investigated the protective effects of BLF in a rat model of sepsis-induced acute lung injury (ALI). The wet/dry ratio, lipid peroxidation, antioxidant markers, total protein, total cell count, inflammatory markers and myeloperoxidase (MPO) levels were assessed. Histopathological analysis was also carried out. BLF treatment reduced the wet/dry ratio of lung tissue by 30.7% and 61.3%, and lipid peroxidation by 22.3% and 67%, at concentrations of 100 and 200 mg/kg, respectively. Superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (Gpx) and catalase were increased by more than 50% under treatment with 200 mg/kg BLF. Inflammatory markers, neutrophils, lymphocytes and total cell count were reduced by more than 50% under treatment with 200 mg/kg BLF. BLF treatment significantly reduced MPO activity, by 28.2% and 74.3%, at concentrations of 100 and 200 mg/kg, respectively. Neutrophilic infiltration and edema were observed in control rats. However, BLF treatment restored intestinal microvilli to the normal range and reduced inflammatory cell invasion. Collectively, these results suggest that BLF is an effective therapeutic agent against sepsis-induced ALI.

    更新日期:2019-11-28
  • Identification of novel B cell epitopes in the fiber protein of serotype 8 Fowl adenovirus
    AMB Express (IF 2.226) Pub Date : 2019-10-31
    Hao Lu, Hongxia Shao, Hongjun Chen, Jianjun Zhang, Weikang Wang, Tuofan Li, Quan Xie, Aijian Qin, Jianqiang Ye

    In recent years, hepatitis-hydropericardium syndrome (HHS) and inclusion body hepatitis (IBH) caused by fowl adenovirus (FAdV) infection have resulted in significant economic losses to the poultry industry worldwide. Epidemiological analysis revealed that serotype FAdV-8 is one of the major pathogenic FAdVs currently prevalent in domestic flocks. Although the fiber protein of FAdV plays vital roles in viral infection and pathogenesis, the B cell epitope in the fiber protein is less known. In this study, two monoclonal antibodies (mAbs) specific to fiber protein of FAdV-8, designated as 4D9 and 5F10, were prepared. Although the mAb 4D9 and 5F10 could not neutralize FAdV-8 infection, 4D9 and 5F10 showed good activities of indirect immunofluorescence, western blot and immunoprecipitation. Epitope analysis revealed that mAb 5F10 recognized 187–219aa in the fiber whereas mAb 4D9 recognized 113–149aa in the fiber. Sequence analysis showed that the epitope recognized by mAb 5F10 was conserve across serotypes FAdV-7, 8a and 8b whereas that for mAb 4D9 was only conserve in FAdV-8b. The generation of mAbs specific to fiber of FAdV-8 and the identification of the novel B cell epitopes here lay the foundation for further studying the antigenicity of the fiber and developing specific diagnosis for FAdV-8.

    更新日期:2019-11-28
  • Application of biological and single-strand conformation polymorphism assays for characterizing potential mild isolates of Citrus tristeza virus for cross protection
    AMB Express (IF 2.226) Pub Date : 2019-10-31
    Sagheer Atta, Ummad ud din Umar, Muhammad Amjad Bashir, Abdul Hannan, Ateeq ur Rehman, Syed Atif Hasan Naqvi, Changyong Zhou

    Citrus tristeza virus (CTV) by killing millions of citrus cultivars grown on sour orange rootstock worldwide has become one of the most dangerous viral pathogen. Characterization of 12 CTV isolates was analyzed by biological indexing. Infected samples of citrus were collected from citrus growing areas of Pakistan and CTV was detected by symptoms on indicator plants and confirmed by direct tissue blot immunoassay (DTBIA). CTV positive samples were graft inoculated on six biological indicator hosts in the study. A standardized protocol was deployed to study biological characteristics of these isolates. All biological indicators induced mild and from mild to moderate reactions against all of the CTV isolates tested. About two isolates produced stem-pitting symptoms from moderate to severe on Mexican lime. CTV strains were further characterized and confirmed by the analysis of p25 gene of CTV isolates using single-strand conformation polymorphism (SSCP) assay. SSCP analysis revealed that most isolates confined only one predominant sequence variant. SSCP profiles of PCR amplified products from CTV isolates showed bands patterns corresponding to mild and sever strain. Three isolates (4MF, 8KBS and 10GS) from different regions and cultivars were identified as potential source of mild strains for cross protection. These results are the best base for mild strain cross protection (MSCP) in the country.

    更新日期:2019-11-28
  • Protective and therapeutic effects of Trianthema portulacastrum against atherosclerosis in male albino rats via G-protein-coupled receptor 124
    AMB Express (IF 2.226) Pub Date : 2019-10-31
    Haoyu Wu, Tianjiao Gao, Yiwei Cao, Jiayu Diao, Fengjun Chang, Jie Qi, Congxia Wang

    Atherosclerosis is a severe cardiovascular disease characterized by narrowing of the lumen, plaque formation, and blood flow turbulence as a result of cholesterol and lipid accumulation in the inner lining of arteries. Bishkhapra (Trianthema portulacastrum Linn.) is a well-known common weed belonging to the family Aizoaceae. Several bioactive compounds have been isolated from this weed and widely used against several diseases. The present study evaluated the protective and therapeutic efficacies of T. portulacastrum against atherosclerosis in a rat model. The animals were divided into the sham, control (diabetes- + atherosclerosis-inducing diet), 100 mg/kg T. portulacastrum treatment, 200 mg/kg T. portulacastrum treatment, and positive control groups. Blood glucose, cholesterol, triglyceride, and other lipid parameters, as well as the expression of G-protein-coupled receptor 124 (GPR124), were measured. Glucose, cholesterol, and triglycerides were significantly reduced to near normal levels. The serum levels of fibrinogen, sVCAM-1, and oxidized low density lipoproteins were substantially increased in control rats. Treatment with the T. portulacastrum extract reversed these levels to near normal levels. The mRNA expression of GPR124 was increased by 150% in the control group. However, treatment with T. portulacastrum extract decreased the mRNA expression up to 40% compared with the control group. Rats treated with 100 and 200 mg/kg T. portulacastrum extract showed a decrease in GPR124 protein expression by 9.5% and 33.3%, respectively. Taken together, the results suggest that an extract of T. portulacastrum is effective against atherosclerosis in streptozotocin-induced diabetic rats.

    更新日期:2019-11-28
  • The effects of Rhodopseudomonas palustris PSB06 and CGA009 with different agricultural applications on rice growth and rhizosphere bacterial communities
    AMB Express (IF 2.226) Pub Date : 2019-10-31
    Luyun Luo, Pei Wang, Zhongying Zhai, Pin Su, Xinqiu Tan, Deyong Zhang, Zhuo Zhang, Yong Liu

    In recent years, the photosynthetic bacteria have been used widely in agriculture, but the effects of different agricultural applications on crop rhizosphere microorganism and crops are lack. In this study, we provide new insights into the structure and composition of the rice root-associated microbiomes as well as the effect on crop of the Rhodopseudomonas palustris(R. palustris) PSB06 and CGA009 at the rice seedling stage with seed immersion and root irrigation. Compare with CK group, the length of stem, the peroxidase (POD), and superoxide dismutase (SOD) activities in PSB06 treatment group was significantly higher, while the length of stem in CGA009 treatment group was significantly higher. The POD and SOD activities in CGA009 treatment groups only were higher slightly than the CK group. In the study, the dominant phyla were Proteobacteria (51.95–61.66%), Bacteroidetes (5.40–9.39%), Acidobacteria (4.50–10.52%), Actinobacteria (5.06–8.14%), Planctomycetes (2.90–4.48%), Chloroflexi (2.23–5.06%) and Firmicutes (2.38–7.30%), accounted for 87% bacterial sequences. The principal coordinate analysis (pCoA) and mantel results showed the two application actions of R. palustris CGA009 and PSB06 had significant effects on rice rhizosphere bacterial communities (p < 0.05). The PSB06 can significantly promote the rice growth and enhance stress resistance of rice at the seedling stage, while the R. palustris CGA009 has no significant effect on rice. Dissimilarity test and canonical correspondence analysis (CCA) results showed that the TN and pH were the key factors affecting rice rhizosphere bacterial community in the seedling stage. This study will provide some guidance advices for the study of the microecological regulation of photosynthetic bacteria on crops.

    更新日期:2019-11-28
  • Chemical diversity in leaf and stem essential oils of Origanum vulgare L. and their effects on microbicidal activities
    AMB Express (IF 2.226) Pub Date : 2019-10-31
    Merajuddin Khan, Shams T. Khan, Mujeeb Khan, Ahmad A. Mousa, Adeem Mahmood, Hamad Z. Alkhathlan

    Essential oils (EOs) from the stems and leaves of Origanum vulgare L. grown in Saudi Arabia and Jordan were analyzed by gas chromatography–mass spectrometry (GC–MS) and GC–flame ionization detector (FID) techniques on two different columns (polar and nonpolar). A detailed phytochemical analysis led to the identification of 153 constituents of these essential oils. Both Saudi and Jordanian plants are classified by chemotypes rich in cymyl-compounds. However, the Saudi Origanum contains carvacrol as the major component and is, thus, characterized as a carvacrol chemotype, while the Jordanian Origanum contains thymol as the major component, and, thus, it is classified as a thymol chemotype. In addition, the antimicrobial activities of the studied EOs and their major components, including carvacrol and thymol, were evaluated against various Gram-positive and Gram-negative microorganisms. All the tested compounds exhibited significant antimicrobial activity against all the tested bacteria. Among them, thymol demonstrated superior activity against all the tested organisms, followed by carvacrol. Moreover, results on oil composition and oil yield of O. vulgare L. from different parts of the world is compared in detail with the present outcomes.

    更新日期:2019-11-28
  • Xszen FHal, a novel tryptophan 5-halogenase from Xenorhabdus szentirmaii
    AMB Express (IF 2.226) Pub Date : 2019-10-31
    Jérémy Domergue, Diane Erdmann, Aurélie Fossey-Jouenne, Jean-Louis Petit, Adrien Debard, Véronique de Berardinis, Carine Vergne-Vaxelaire, Anne Zaparucha

    Flavin-dependent halogenases (FHals) catalyse the halogenation of electron-rich substrates, mainly aromatics. Halogenated compounds have many applications, as pharmaceutical, agrochemicals or as starting materials for the synthesis of complex molecules. By exploring the sequenced bacterial diversity, we discovered and characterized XszenFHal, a novel FHal from Xenorhabdus szentirmaii, a symbiotic bacterium of entomopathogenic nematode. The substrate scope of XszenFHal was examined and revealed activities towards tryptophan, indole and indole derivatives, leading to the formation of the corresponding 5-chloro products. XszenFHal makes a valuable addition to the panel of flavin-dependent halogenases already discovered and enriches the potential for biotechnology applications by allowing access to 5-halogenated indole derivatives.

    更新日期:2019-11-28
  • Molecular characterization of hypothetical scaffolding-like protein S1 in multienzyme complex produced by Paenibacillus curdlanolyticus B-6
    AMB Express (IF 2.226) Pub Date : 2019-10-31
    Patthra Pason, Junjarus Sermsathanaswadi, Rattiya Waeonukul, Chakrit Tachaapaikoon, Sirilak Baramee, Khanok Ratanakhanokchai, Akihiko Kosugi

    Paenibacillus curdlanolyticus B-6 produces an extracellular multienzyme complex containing a hypothetical scaffolding-like protein and several xylanases and cellulases. The largest (280-kDa) component protein, called S1, has cellulose-binding ability and xylanase activity, thus was considered to function like the scaffolding proteins found in cellulosomes. S1 consists of 863 amino acid residues with predicted molecular mass 91,029 Da and includes two N-terminal surface layer homology (SLH) domains, but most of its sequence shows no homology with proteins of known function. Native S1 (nS1) was highly glycosylated. Purified nS1 and recombinant Xyn11A (rXyn11A) as a major xylanase subunit could assemble in a complex, but recombinant S1 (rS1) could not interact with rXyn11A, indicating that S1 glycosylation is necessary for assembly of the multienzyme complex. nS1 and rS1 showed weak, typical endo-xylanase activity, even though they have no homology with known glycosyl hydrolase family enzymes. S1 and its SLH domains bound tightly to the peptide-glycan layer of P. curdlanolyticus B-6, microcrystalline cellulose, and insoluble xylan, indicating that the SLHs of S1 bind to carbohydrate polymers and the cell surface. When nS1 and rXyn11A were co-incubated with birchwood xylan, the degradation ability was synergistically increased compared with that for each protein; however synergy was not observed for rS1 and rXynA. These results indicate that S1 may have a scaffolding protein-like function by interaction with enzyme subunits and polysaccharides through its glycosylated sites and SLH domains.

    更新日期:2019-11-28
  • Abiotic environmental factors override phytoplankton succession in shaping both free-living and attached bacterial communities in a highland lake
    AMB Express (IF 2.226) Pub Date : 2019-10-31
    Huan Wang, Rong Zhu, Xiaolin Zhang, Yun Li, Leyi Ni, Ping Xie, Hong Shen

    Bacterial communities are an important part of biological diversity and biogeochemical cycling in aquatic ecosystems. In this study, the relationship amongst the phytoplankton species composition and abiotic environmental factors on seasonal changes in the community composition of free-living and attached bacteria in Lake Erhai were studied. Using Illumina high-throughput sequencing, we found that the impact of environmental factors on both the free-living and attached bacterial community composition was greater than that of the phytoplankton community, amongst which total phosphorus, Secchi disk, water temperature, dissolved oxygen and conductivity strongly influenced bacterial community composition. Microcystis blooms associated with subdominant Psephonema occurred during the summer and autumn, and Fragilaria, Melosira and Mougeotia were found at high densities in the other seasons. Only small numbers of algal species-specific bacteria, including Xanthomonadaceae (Proteobacteria) and Alcaligenaceae (Betaproteobacteria), were tightly coupled to Microcystis and Psephonema during Microcystis blooms. Redundancy analysis showed that although the composition of the bacterial communities was controlled by species composition mediated by changes in phytoplankton communities and abiotic environmental factors, the impact of the abiotic environment on both free-living and attached bacterial community compositions were greater than the impact of the phytoplankton community. These results suggest that the species composition of both free-living and attached bacterial communities are affected by abiotic environmental factors, even when under strong control by biotic factors, particularly dominant genera of Microcystis and Psephonema during algal blooms.

    更新日期:2019-11-28
  • Effect of the inoculation of plant growth-promoting rhizobacteria on the photosynthetic characteristics of Sambucus williamsii Hance container seedlings under drought stress.
    AMB Express (IF 2.226) Pub Date : 2019-11-02
    Fangchun Liu,Hailin Ma,Lin Peng,Zhenyu Du,Bingyao Ma,Xinghong Liu

    Plant growth-promoting rhizobacteria (PGPR) are beneficial bacteria that survive within the range of plant rhizosphere and can promote plant growth. The effects of PGPR in promoting plant growth, activating soil nutrients, reducing fertilizer application, and improving the resistance of plant inducible system have been widely investigated. However, few studies have investigated PGPR as elicitors of tolerance to abiotic stresses, especially drought stress. In this study, the effects of Acinetobacter calcoaceticus X128 on the photosynthetic rate (Pn), stomatal conductance (Gs), intracellular CO2 concentration (Ci), and total chlorophyll content [Chl(a+b)] of Sambucus williamsii Hance seedling leaves under moderate drought stress and drought-rewatering conditions were determined. Compared with those of uninoculated seedlings, the average Pn values during the entire drought stress of inoculated seedlings increased by 12.99%. As the drought duration was lengthened, Ci of uninoculated leaves continued to increase after rapidly declining, whereas Gs continuously decreased. Furthermore, their photosynthetic properties were simultaneously restricted by stomatal and non-stomatal factors. After X128 inoculation, Ci and Gs of S. williamsii Hance leaves continued to decrease, and their photosynthetic properties were mainly restricted by stomatal factors. At the end of the drought stress, water stress reduced [Chl(a + b)] of S. williamsii Hance leaves by 13.49%. However, X128 inoculation decreased this deficit to only 7.39%. After water supply was recovered, Pn, Gs, and [Chl(a+b)] in uninoculated leaves were reduced by 14.23%, 12.02%, and 5.86%, respectively, relative to those under well-watered conditions. However, Ci increased by 6.48%. Compared with those of uninoculated seedlings, Pn, Gs, and [Chl(a+b)] in X128-inoculated seedlings were increased by 9.83%, 9.30%, and 6.85%, respectively. Therefore, the inoculation of X128 under arid environments can mitigate the reduction of chlorophyll, delay the restriction caused by non-stomatal factors to Pn in plant leaves under water stress, and can be more conducive to the recovery of photosynthetic functions of leaves after water supply is recovered.

    更新日期:2019-11-01
  • Nematicidal potential of Streptomyces antibioticus strain M7 against Meloidogyne incognita.
    AMB Express (IF 2.226) Pub Date : 2019-10-24
    Manish Sharma,Shivam Jasrotia,Puja Ohri,Rajesh Kumari Manhas

    Meloidogyne spp. are microscopic, obligatory endoparasites with worldwide distribution which cause severe damage to agricultural crops. The present study revealed the nematicidal activity of Streptomyces antibioticus strain M7 against Meloidogyne incognita. The culture supernatant of the isolate caused 100% J2 mortality after 24 h and inhibited egg hatching (only 3%). In addition, the nematicidal activity of actinomycins V, X2 and D purified from strain M7 was also checked. In vitro studies displayed 97.0-99.0% juvenile mortality and 28.0-44.0% egg hatching after 168 h at 240 µg/ml of actinomycin, with LD50 (lethal dose) values of 28-120 µg/ml. In vivo study further validated the nematicidal activity of strain M7, where nematode infested tomato plants treated with culture supernatant/cells/solvent extract showed reduction in root galls and egg masses per plant by 50.0-62.06% and 53.48-76.74%, respectively, and significantly enhanced the shoot length (54.67-76.39%), root length (36.45-64.88%), shoot fresh weight (111-171.77%), root fresh weight (120-163.33%), shoot dry weight (54.45-145.45%), and root dry weight (100-133.3%) over the nematode infested plants treated with water. Furthermore, tomato plants treated with cells/culture supernatant/extract of strain M7 without nematode infestation also showed significant increase in various plant growth parameters. Thus, the outcome of the study revealed the potential of S. antibioticus strain M7 and actinomycins produced from it to be developed as safe nematicidal agents to control the root knot nematodes, and to increase the crop yield.

    更新日期:2019-11-01
  • Codon harmonization reduces amino acid misincorporation in bacterially expressed P. falciparum proteins and improves their immunogenicity.
    AMB Express (IF 2.226) Pub Date : 2019-10-21
    Neeraja Punde,Jennifer Kooken,Dagmar Leary,Patricia M Legler,Evelina Angov

    Codon usage frequency influences protein structure and function. The frequency with which codons are used potentially impacts primary, secondary and tertiary protein structure. Poor expression, loss of function, insolubility, or truncation can result from species-specific differences in codon usage. "Codon harmonization" more closely aligns native codon usage frequencies with those of the expression host particularly within putative inter-domain segments where slower rates of translation may play a role in protein folding. Heterologous expression of Plasmodium falciparum genes in Escherichia coli has been a challenge due to their AT-rich codon bias and the highly repetitive DNA sequences. Here, codon harmonization was applied to the malarial antigen, CelTOS (Cell-traversal protein for ookinetes and sporozoites). CelTOS is a highly conserved P. falciparum protein involved in cellular traversal through mosquito and vertebrate host cells. It reversibly refolds after thermal denaturation making it a desirable malarial vaccine candidate. Protein expressed in E. coli from a codon harmonized sequence of P. falciparum CelTOS (CH-PfCelTOS) was compared with protein expressed from the native codon sequence (N-PfCelTOS) to assess the impact of codon usage on protein expression levels, solubility, yield, stability, structural integrity, recognition with CelTOS-specific mAbs and immunogenicity in mice. While the translated proteins were expected to be identical, the translated products produced from the codon-harmonized sequence differed in helical content and showed a smaller distribution of polypeptides in mass spectra indicating lower heterogeneity of the codon harmonized version and fewer amino acid misincorporations. Substitutions of hydrophobic-to-hydrophobic amino acid were observed more commonly than any other. CH-PfCelTOS induced significantly higher antibody levels compared with N-PfCelTOS; however, no significant differences in either IFN-γ or IL-4 cellular responses were detected between the two antigens.

    更新日期:2019-11-01
  • Towards the understanding of the enzymatic cleavage of polyisoprene by the dihaem-dioxygenase RoxA.
    AMB Express (IF 2.226) Pub Date : 2019-10-19
    Georg Schmitt,Jakob Birke,Dieter Jendrossek

    Utilization of polyisoprene (natural rubber) as a carbon source by Steroidobacter cummioxidans 35Y (previously Xanthomonas sp. strain 35Y) depends on the formation and secretion of rubber oxygenase A (RoxA). RoxA is a dioxygenase that cleaves polyisoprene to 12-oxo-4,8-dimethyl-trideca-4,8-diene-1-al (ODTD), a suitable growth substrate for S. cummioxidans. RoxA harbours two non-equivalent, spectroscopically distinguishable haem centres. A dioxygen molecule is bound to the N-terminal haem of RoxA and identifies this haem as the active site. In this study, we provide insights into the nature of this unusually stable dioxygen-haem coordination of RoxA by a re-evaluation of previously published together with newly obtained biophysical data on the cleavage of polyisoprene by RoxA. In combination with the meanwhile available structure of RoxA we are now able to explain several uncommon and previously not fully understood features of RoxA, the prototype of rubber oxygenases in Gram-negative rubber-degrading bacteria.

    更新日期:2019-11-01
  • Recombinant expressing angiopep-2 fused anti-VEGF single chain Fab (scFab) could cross blood-brain barrier and target glioma.
    AMB Express (IF 2.226) Pub Date : 2019-10-17
    Xuemei Ji,Hongyan Wang,Yue Chen,Junfei Zhou,Yu Liu

    In 2009, the FDA approved bevacizumab for the treatment of adult patients diagnosed with recurrent glioblastoma. However, the poor permeability of the macromolecules across the blood-brain barrier, determined by multifactorial anatomical and physiological milieu, restricts the clinical therapeutic effect of bevacizumab. The low-density lipoprotein receptor related protein 1 (LRP1) is highly expressed in the endothelial cells of the brain capillary and the glioma cells. Angiopep-2 (ANG) is a 19-aa oligopeptide that can bind to LRP1 and penetrate the blood-brain barrier by receptor-mediated transport. Therefore, ANG can be used as a dual-targeting drug delivery carrier into the brain and the glioma sites. In this study, ANG gene was fused with the C-terminal domain of single-chain antigen binding fragment (scFab) of the anti-VEGF antibody and recombinant scFab-ANG protein was expressed and purified using Rosatte (DE3) strain. We confirmed that ANG could carry anti-VEGF-scFab, penetrate a three-dimensional model of the brain tumor, and cross the hCMEC/D3 monolayer in the in vitro blood-brain barrier model. The animal experiments demonstrated that 3 h after the tail intravenous protein injection, the fluorescent signals in the brains of the mice in the scFab-ANG group were stronger than that in the scFab group. Furthermore, the study of the in situ rat glioma model shows that scFab-ANG could target glioma while anti-VEGF-scFab could not. These findings indicate that scFab-ANG had stronger transepithelial permeability and glioma targeting capacity. Thus, it can be a potential candidate drug for glioblastoma therapy.

    更新日期:2019-11-01
  • Development of a simple and high-yielding fed-batch process for the production of porcine circovirus type 2 virus-like particle subunit vaccine.
    AMB Express (IF 2.226) Pub Date : 2019-10-13
    Wenlong Cao,Hui Cao,Xiaoping Yi,Yingping Zhuang

    The cap protein is encoded by the orf2 gene of porcine circovirus type 2 (PCV2) has the main antigen epitope of PCV2 and can form virus-like particles (VLPs), which are expressed in insect cells. PCV2-VLPs can effectively inhibit PCV2 replication as a subunit vaccine. In this study, a robust and reliable fed-batch process was successfully developed for the production of PCV2-VLPs by Sf9 cells. The feeding solution, feeding strategy, and cell density at infection were optimized to maximize the final PCV2-VLPs production yields. The cell density at infection and the volumetric PCV2-VLPs production reached 12 × 106 cells/mL and 110 mg/L, respectively, which yielded 3- and 3.6-fold enhancements compared to the batch culture. The PCV2-VLPs produced in fed-batch culture were not different from the PCV2-VLPs produced in a batch culture in an immunity test. A highly efficient production process was produced for PCV2-VLPs subunit vaccines, which could provide an effective means for the industrial production of PCV2 vaccines.

    更新日期:2019-11-01
  • Effects of exogenous lipids and cold acclimation on lycopene production and fatty acid composition in Blakeslea trispora.
    AMB Express (IF 2.226) Pub Date : 2019-10-13
    Feng Lingran,Wang Qiang,Yu Xiaobin,Fred Kwame

    Exogenous lipids serving as stimulators to improve lycopene production in Blakeslea trispora have been widely reported. However, the selection basis of exogenous lipids and their effects on intracellular lipids are not very clear. In this study, five plant oils with different fatty acid compositions were selected to investigate their effects on lycopene production, fatty acid composition and the desaturation degree of intracellular lipids. Among the oils, soybean oil, with a fatty acid composition similar to that of mycelium, exhibited the best stimulating effect on lycopene formation (improvement of 82.1%). The plant oils enhanced the total content of intracellular lipids and the desaturation degree of reserve lipids due to the alteration of fatty acid composition, especially in neutral lipids. Lycopene production was increased with the improved desaturation degree of intracellular lipids, which may be attributed to the enhancement of storage capacity for lycopene in storage lipid, thus reducing the feedback regulation of free lycopene. In addition, the increase of the desaturation degree of reserve lipids through temperature-changing fermentation also enhanced lycopene production. The present study could serve as a basis for a better understanding of the relationship between the fatty acid composition of reserve lipids and lycopene production.

    更新日期:2019-11-01
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