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  • Chitin/chitosan derivatives and their interactions with microorganisms: a comprehensive review and future perspectives
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-16
    Muhammad Shahid Riaz Rajoka; Hafiza Mahreen Mehwish; Yiguang Wu; Liqing Zhao; Yasir Arfat; Kashif Majeed; Shoaib Anwaar

    Chitosan, obtained as a result of the deacetylation of chitin, one of the most important naturally occurring polymers, has antimicrobial properties against fungi, and bacteria. It is also useful in other fields, including: food, biomedicine, biotechnology, agriculture, and the pharmaceutical industries. A literature survey shows that its antimicrobial activity depends upon several factors such as: the pH, temperature, molecular weight, ability to chelate metals, degree of deacetylation, source of chitosan, and the type of microorganism involved. This review will focus on the in vitro and in vivo antimicrobial properties of chitosan and its derivatives, along with a discussion on its mechanism of action during the treatment of infectious animal diseases, as well as its importance in food safety. We conclude with a summary of the challenges associated with the uses of chitosan and its derivatives.

    更新日期:2020-01-17
  • Current progress on the production, modification, and applications of bacterial cellulose
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-14
    Francisco German Blanco Parte; Shella Permatasari Santoso; Chih-Chan Chou; Vivek Verma; Hsueh-Ting Wang; Suryadi Ismadji; Kuan-Chen Cheng

    Adoption of biomass for the development of biobased products has become a routine agenda in evolutionary metabolic engineering. Cellulose produced by bacteria is a “rising star” for this sustainable development. Unlike plant cellulose, bacterial cellulose (BC) shows several unique properties like a high degree of crystallinity, high purity, high water retention, high mechanical strength, and enhanced biocompatibility. Favored with those extraordinary properties, BC could serve as ideal biomass for the development of various industrial products. However, a low yield and the requirement for large growth media have been a persistent challenge in mass production of BC. A significant number of techniques has been developed in achieving efficient BC production. This includes the modification of bioreactors, fermentation parameters, and growth media. In this article, we summarize progress in metabolic engineering in order to solve BC growth limitation. This article emphasizes current engineered BC production by using various bioreactors, as well as highlighting the structure of BC fermented by different types of engineered-bioreactors. The comprehensive overview of the future applications of BC, aims to provide readers with insight into new economic opportunities of BC and their modifiable properties for various industrial applications. Modifications in chemical composition, structure, and genetic regulation, which preceded the advancement of BC applications, were also emphasized.

    更新日期:2020-01-15
  • Application of experimental designs and response surface methods in screening and optimization of reverse micellar extraction
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-13
    Sharifah Fathiyah Sy Mohamad; Farhan Mohd Said; Mimi Sakinah Abdul Munaim; Shahril Mohamad; Wan Mohd Azizi Wan Sulaiman

    Reverse micellar extraction (RME) has emerged as a versatile and efficient tool for downstream processing (DSP) of various biomolecules, including structural proteins and enzymes, due to the substantial advantages over conventional DSP methods. However, the RME system is a complex dependency of several parameters that influences the overall selectivity and performance of the RME system, hence this justifies the need for optimization to obtain higher possible extraction results. For the last two decades, many experimental design strategies for screening and optimization of RME have been described in literature. The objective of this article is to review the use of different experimental designs and response surface methodologies that are currently used to screen and optimize the RME system for various types of biomolecules. Overall, this review provides the rationale for the selection of appropriate screening or optimization techniques for the parameters associated with both forward and backward extraction during the RME of biomolecules.

    更新日期:2020-01-14
  • Phytohormones regulate convergent and divergent responses between individual and combined drought and pathogen infection
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-13
    Aarti Gupta; Ranjita Sinha; Joel Lars Fernandes; Mostafa Abdelrahman; David J. Burritt; Lam-Son Phan Tran

    Plants exposed to the combination of drought and pathogen infections are in a unique state, different from that of plants exposed to each stress alone. Plants undergo major hormonal changes during drought and/or pathogen infection, highlighting the importance of hormones as crucial mediators of plant stress responses. Evidence from individual stress studies has shown that drought and pathogen infection have both different and overlapping impacts on hormone metabolism and hormone-associated signal transduction pathways. Thus, under the combination of drought and pathogen infection, a reprograming of hormone levels and related signaling networks is inevitable. This process delivers data from plants exposed to individual stressors inadequate for predicting how hormone levels and related signaling networks will change in plants exposed to a combination of stressors. Furthermore, the yield of crop plants, determined by their capacity for stress acclimatization and resistance to pathogen infection, will be underpinned by interactions among the hormone pathways. Although many studies have been conducted to understand the molecular mechanisms associated with plant responses to combinations of stressors, the interactions that occur among hormones are far from being well-understood. We provide here an overview and evaluation of various reports on crosstalk or overlapping hormonal responses from individual stress studies and how the combination of drought and pathogen infection modulates hormone levels and their associated signaling pathways in plant responses to these combined stresses. We also give a brief overview of the importance of overlapping plant responses for the production of crop plants resistant to individual and combined stressors under natural environmental conditions.

    更新日期:2020-01-14
  • Biochemical interactions between LPS and LPS-binding molecules
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-13
    Arantza Basauri; Cristina González-Fernández; Marcos Fallanza; Eugenio Bringas; Raúl Fernandez-Lopez; Laura Giner; Gabriel Moncalián; Fernando de la Cruz; Inmaculada Ortiz

    Lipopolysaccharide (LPS), the major component of the outer membrane of Gram-negative bacteria, often pose a serious risk not only when delivered in the bloodstream but also in air, the environment and several industrial fields such as pharmaceutics or food. LPS is constituted of three regions; the O-specific chain, the core region and the lipid A, which is the responsible segment of the toxicity. Previous literature dealt with the study of lipid A, its potential ligands as well as the mechanisms of Lipid A interactions that, among other applications, establish the basis for detection methods such as Limulus Amebocyte Lysate (LAL) assays and emerging biosensoring techniques. However, quantifying LPS binding affinity is an urgent need that still requires thorough studies. In this context, this work reviews the molecules that bind LPS, highlighting quantitative affinity parameters. Moreover, state of the art methods to analyze the affinity and kinetics of lipid-ligand interactions are also reviewed and different techniques have been briefly described. Thus, first, we review existing information on LPS ligands, classifying them into three main groups and targeting the comparison of molecules in terms of their interaction affinities and, second, we establish the basis for further research aimed at the development of effective methods for LPS detection and removal.

    更新日期:2020-01-14
  • Kinetic modeling of Chinese hamster ovary cell culture: factors and principles
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-12
    Peifeng Tang; Jianlin Xu; Alastair Louey; Zhijun Tan; Andrew Yongky; Shaoyan Liang; Zheng Jian Li; Yongyan Weng; Shijie Liu

    As a host for therapeutic protein expression, Chinese hamster ovary (CHO) cells are widely utilized in the mainstream biopharmaceutical industry. Cell culture process development plays an important role in transitioning laboratory research to manufacturing. Among different mathematic tools, kinetic modeling is commonly achieved through analyzing cell culture data to design process parameters, optimize media, and scale up bioreactors. In this review, we examine key factors for upstream process development, and summarize currently used kinetic modeling strategies. In addition, two original examples of kinetic modeling application optimizing cell culture performance are presented. A comprehensive understanding is provided for the kinetic modeling and its applications in cell culture process development.

    更新日期:2020-01-13
  • Opportunities to debottleneck the downstream processing of the oncolytic measles virus
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-09
    Daniel Loewe; Hauke Dieken; Tanja A. Grein; Tobias Weidner; Denise Salzig; Peter Czermak

    Oncolytic viruses (including measles virus) offer an alternative approach to reduce the high mortality rate of late-stage cancer. Several measles virus strains infect and lyse cancer cells efficiently, but the broad application of this therapeutic concept is hindered by the large number of infectious particles required (108–1012 TCID50 per dose). The manufacturing process must, therefore, achieve high titers of oncolytic measles virus (OMV) during upstream production and ensure that the virus product is not damaged during purification by applying appropriate downstream processing (DSP) unit operations. DSP is currently a production bottleneck because there are no specific platforms for OMV. Infectious OMV must be recovered as intact, enveloped particles, and host cell proteins and DNA must be reduced to acceptable levels to meet regulatory guidelines that were developed for virus-based vaccines and gene therapy vectors. Handling such high viral titers and process volumes is technologically challenging and expensive. This review considers the state of the art in OMV purification and looks at promising DSP technologies. We discuss here the purification of other enveloped viruses where such technologies could also be applied to OMV. The development of DSP technologies tailored for enveloped viruses is necessary to produce sufficient titers for virotherapy, which could offer hope to millions of patients suffering from incurable cancer.

    更新日期:2020-01-13
  • Bioengineering oligomerization and monomerization of enzymes: learning from natural evolution to matching the demands for industrial applications
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-08
    Hu Liu; Mingming Cao; Ying Wang; Bo Lv; Chun Li

    It is generally accepted that oligomeric enzymes evolve from their monomeric ancestors, and the evolution process generates superior structural benefits for functional advantages. Furthermore, adjusting the transition between different oligomeric states is an important mechanism for natural enzymes to regulate their catalytic functions for adapting environmental fluctuations in nature, which inspires researchers to mimic such a strategy to develop artificially oligomerized enzymes through protein engineering for improved performance under specific conditions. On the other hand, transforming oligomeric enzymes into their monomers is needed in fundamental research for deciphering catalytic mechanisms as well as exploring their catalytic capacities for better industrial applications. In this article, strategies for developing artificially oligomerized and monomerized enzymes are reviewed and highlighted by their applications. Furthermore, advances in the computational prediction of oligomeric structures are introduced, which would accelerate the systematic design of oligomeric and monomeric enzymes. Finally, the current challenges and future directions in this field are discussed.

    更新日期:2020-01-09
  • Lung-on-a-chip: the future of respiratory disease models and pharmacological studies
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-06
    Jesus Shrestha; Sajad Razavi Bazaz; Hamidreza Aboulkheyr Es; Dania Yaghobian Azari; Benjamin Thierry; Majid Ebrahimi Warkiani; Maliheh Ghadiri

    Recently, organ-on-a-chip models, which are microfluidic devices that mimic the cellular architecture and physiological environment of an organ, have been developed and extensively investigated. The chips can be tailored to accommodate the disease conditions pertaining to many organs; and in the case of this review, the lung. Lung-on-a-chip models result in a more accurate reflection compared to conventional in vitro models. Pharmaceutical drug testing methods traditionally use animal models in order to evaluate pharmacological and toxicological responses to a new agent. However, these responses do not directly reflect human physiological responses. In this review, current and future applications of the lung-on-a-chip in the respiratory system will be discussed. Furthermore, the limitations of current conventional in vitro models used for respiratory disease modeling and drug development will be addressed. Highlights of additional translational aspects of the lung-on-a-chip will be discussed in order to demonstrate the importance of this subject for medical research.

    更新日期:2020-01-07
  • Sphingomonas: from diversity and genomics to functional role in environmental remediation and plant growth
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-06
    Sajjad Asaf; Muhammad Numan; Abdul Latif Khan; Ahmed Al-Harrasi

    The species belonging to the Sphingomonas genus possess multifaceted functions ranging from remediation of environmental contaminations to producing highly beneficial phytohormones, such as sphingan and gellan gum. Recent studies have shown an intriguing role of Sphingomonas species in the degradation of organometallic compounds. However, the actual biotechnological potential of this genus requires further assessment. Some of the species from the genus have also been noted to improve plant-growth during stress conditions such as drought, salinity, and heavy metals in agricultural soil. This role has been attributed to their potential to produce plant growth hormones e.g. gibberellins and indole acetic acid. However, the current literature is scattered, and some of the important areas, such as taxonomy, phylogenetics, genome mapping, and cellular transport systems, are still being overlooked in terms of elucidation of the mechanisms behind stress-tolerance and bioremediation. In this review, we elucidated the prospective role and function of this genus for improved utilization during environmental biotechnology.

    更新日期:2020-01-07
  • Advanced strategy for metabolite exploration in filamentous fungi
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-06
    Huaxiang Deng; Yajun Bai; Tai-Ping Fan; Xiaohui Zheng; Yujie Cai

    Filamentous fungi comprise an abundance of gene clusters that encode high-value metabolites, whereas affluent gene clusters remain silent during laboratory conditions. Complex cellular metabolism further limits these metabolite yields. Therefore, diverse strategies such as genetic engineering and chemical mutagenesis have been developed to activate these cryptic pathways and improve metabolite productivity. However, lower efficiencies of gene modifications and screen tools delayed the above processes. To address the above issues, this review describes an alternative design-construction evaluation optimization (DCEO) approach. The DCEO tool provides theoretical and practical principles to identify potential pathways, modify endogenous pathways, integrate exogenous pathways, and exploit novel pathways for their diverse metabolites and desirable productivities. This DCEO method also offers different tactics to balance the cellular metabolisms, facilitate the genetic engineering, and exploit the scalable metabolites in filamentous fungi.

    更新日期:2020-01-07
  • Exploring the feasibility of sewage treatment by algal–bacterial consortia
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-06
    Jixiang Yang; Wenxin Shi; Fang Fang; Jinsong Guo; Lunhui Lu; Yan Xiao; Xin Jiang

    Current biological wastewater treatment is energy intensive. The application of algal–bacterial consortia to treat wastewater has recently attracted considerable attention because mechanical aeration is unnecessary. Therefore, algal–bacterial bioreactors are emerging as alternatives to activated sludge-based bioprocesses. Most studies have used a plate substratum to support the growth of algal–bacterial biofilms, which results in low reactor efficiencies. Usually, 2–10 days are required for targeted pollutant removal effects. Substratum structures can significantly influence reactor efficiencies. Indeed, substratum-free biofilms (granules) generally achieve high reactor efficiencies that rapidly form. 7–12 h are sufficient for a high-level pollutant removal efficiency. However, granule stability must be validated during long-term experiments (>1 year) involving real wastewater. In addition, the application of algal–bacterial membrane bioreactors represents a novel treatment approach. In membrane bioreactors, good reactor efficiencies and stabilities can be achieved. However, the maximum capacity of algal–bacterial membrane bioreactors requires further investigation. In addition, an accurate model for pollutant removal kinetics in algal–bacterial reactors is not yet available but is necessary for reactor control and up-scaling. The microbial and physical structures of algal–bacterial biofilms require more studies to clarify the system. Finally, the operational costs of algal–bacterial systems must be kept low in order to enhance their potential for sewage treatment at large scales. Good illumination control and recycling biomass for biodiesel or methane production could be applied to reducing the operation cost.

    更新日期:2020-01-07
  • CRISPR/Cas9 genome editing through in planta transformation
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-05
    Nikolay E. Zlobin; Marina V. Lebedeva; Vasiliy V. Taranov

    In this review, the application of CRISPR/Cas9 plant genome editing using alternative transformation methods is discussed. Genome editing by the CRISPR/Cas9 system is usually implemented via the generation of transgenic plants carrying Cas9 and sgRNA genes in the genome. Transgenic plants are usually developed by in vitro regeneration from single transformed cells, which requires using different in vitro culture-based methods. Despite their common application, these methods have some disadvantages and limitations. Thus, some methods of plant transformation that do not depend on in vitro regeneration have been developed. These methods are known as “in planta” transformation. The main focus of this review is the so-called floral dip in planta transformation method, although other approaches are also described. The main features of in planta transformation in the context of CRISPR/Cas9 genome editing are discussed. Furthermore, multiple ways to increase the effectiveness of this approach and to broaden its use in different plant species are considered.

    更新日期:2020-01-06
  • Citric acid bioproduction: the technological innovation change
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2020-01-05
    Alessia Amato; Alessandro Becci; Francesca Beolchini

    Citric acid is considered one of the most valuable weak organic acids on the market and its production by biotechnological approaches is a very interesting topic. Despite the related scientific research, the literature still lacks a state of the art for the technological innovation change, necessary for a study of the inventions designed for real scale implementation. In this context, the present review looks to account for more than 100 worldwide patents (1929–2018), necessary for the identification of the innovative markets and the most promising fields for economic investments. This deepened study identified an increasing invention number, combined with the current worldwide citric acid export flows, with China as the leader (with an economic contribution of 75%, in 2017). In order to satisfy the requests of the market which has moved toward a circular economy, the possibility to use waste substrates represents one of the main options considered in the recent patents. The discussion highlights the sustainability improvement, achieved by the conversion from a submerged technology to a solid-state fermentation (koji process). The listed results are essential for both a scientific audience and the stakeholders involved in citric acid production, in order to have a complete and updated overview of this topic.

    更新日期:2020-01-06
  • The interaction of phages and bacteria: the co-evolutionary arms race
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2019-12-02
    Fatemeh Safari, Mehrdad Sharifi, Safar Farajnia, Bahman Akbari, Mohammad Karimi Baba Ahmadi, Manica Negahdaripour, Younes Ghasemi

    Since the dawn of life, bacteria and phages are locked in a constant battle and both are perpetually changing their tactics to overcome each other. Bacteria use various strategies to overcome the invading phages, including adsorption inhibition, restriction–modification (R/E) systems, CRISPR–Cas (clustered regularly interspaced short palindromic repeats–CRISPR-associated proteins) systems, abortive infection (Abi), etc. To counteract, phages employ intelligent tactics for the nullification of bacterial defense systems, such as accessing host receptors, evading R/E systems, and anti-CRISPR proteins. Intense knowledge about the details of these defense pathways is the basis for their broad utilities in various fields of research from microbiology to biotechnology. Hence, in this review, we discuss some strategies used by bacteria to inhibit phage infections as well as phage tactics to circumvent bacterial defense systems. In addition, the application of these strategies will be described as a lesson learned from bacteria and phage combats. The ecological factors that affect the evolution of bacterial immune systems is the other issue represented in this review.

    更新日期:2019-12-03
  • Recent development of advanced biotechnology for wastewater treatment
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2019-11-05
    Huan Yi, Minfang Li, Xiuqin Huo, Guangming Zeng, Cui Lai, Danlian Huang, Ziwen An, Lei Qin, Xigui Liu, Bisheng Li, Shiyu Liu, Yukui Fu, Mingming Zhang

    The importance of highly efficient wastewater treatment is evident from aggravated water crises. With the development of green technology, wastewater treatment is required in an eco-friendly manner. Biotechnology is a promising solution to address this problem, including treatment and monitoring processes. The main directions and differences in biotreatment process are related to the surrounding environmental conditions, biological processes, and the type of microorganisms. It is significant to find suitable biotreatment methods to meet the specific requirements for practical situations. In this review, we first provide a comprehensive overview of optimized biotreatment processes for treating wastewater during different conditions. Both the advantages and disadvantages of these biotechnologies are discussed at length, along with their application scope. Then, we elaborated on recent developments of advanced biosensors (i.e. optical, electrochemical, and other biosensors) for monitoring processes. Finally, we discuss the limitations and perspectives of biological methods and biosensors applied in wastewater treatment. Overall, this review aims to project a rapid developmental path showing a broad vision of recent biotechnologies, applications, challenges, and opportunities for scholars in biotechnological fields for “green” wastewater treatment.

    更新日期:2019-11-06
  • Recent advances in the improvement of enzyme thermostability by structure modification
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2019-11-05
    Zhe Xu, Yu-Ke Cen, Shu-Ping Zou, Ya-Ping Xue, Yu-Guo Zheng

    Thermostability is considered to be an important parameter to measure the feasibility of enzymes for industrial applications. Generally, higher thermostability makes an enzyme more competitive and desirable in industry. However, most natural enzymes show poor thermostability, which restricts their application. Protein structure modification is a desirable method to improve enzyme properties. In recent years, tremendous progress has been achieved in protein thermostability engineering. In this review, we provide a systemic overview on the approaches of protein structure modification for the improvement of enzyme thermostability during the last decade. Structure modification approaches, including the introduction of non-covalent interactions and covalent bonds, increase of proline and/or decrease in glycine, reinforcement of subunit–subunit interactions, introduction of glycosylation sites, truncation and cyclization have been highlighted.

    更新日期:2019-11-06
  • Processing of apple pomace for bioactive molecules.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-12-04
    Shashi Bhushan,Kalpana Kalia,Madhu Sharma,Bikram Singh,P S Ahuja

    The growth of horticulture industries worldwide has generated huge quantities of fruit wastes (25%-40% of the total fruits processed). These residues are generally a good source of carbohydrates, especially cell wall polysaccharides and other functionally important bioactive molecules such as proteins, vitamins, minerals and natural antioxidants. "Apple pomace" is a left-over solid biomass with a high moisture content, obtained as a by-product during the processing of apple fruits for juice, cider or wine preparation. Owing to the high carbohydrate content, apple pomace is used as a substrate in a number of microbial processes for the production of organic acids, enzymes, single cell protein, ethanol, low alcoholic drinks and pigments. Recent research trends reveal that there is an increase in the utilization of apple pomace as a food processing residue for the extraction of value added products such as dietary fibre, protein, natural antioxidants, biopolymers, pigments and compounds with unique properties. However, the central dogma is still the stability, safety and economic feasibility of the process(s)/product(s) developed. This review is mainly focused on assessing recent research developments in extraction, isolation and characterization of bioactive molecules from apple pomace, along with their commercial utilization, in food fortification.

    更新日期:2019-11-01
  • Current [corrected] trends in phytosynthesis of metal nanoparticles.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-12-04
    Mahendra Rai,Alka Yadav,Aniket Gade

    Nanotechnology is emerging as a field of applied science and technology. Synthesis of nanoparticles is done by various physical and chemical methods but the biological system is gaining attention as an eco-friendly technique. The biosynthetic method employing plant parts is proving as a simple and cost-effective method for the synthesis of nanoparticles. The present mini review focuses on the different systems utilized for the synthesis of nanoparticles with special emphasis on the use of plants for the synthesis process, its applications and future directions.

    更新日期:2019-11-01
  • Organophosphate degrading microorganisms and enzymes as biocatalysts in environmental and personal decontamination applications.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-12-04
    Simo Yair,Butnaro Ofer,Eisenkraft Arik,Shrot Shai,Rosman Yossi,Dushnitsky Tzvika,Krivoy Amir

    One of the major challenges in dealing with chemical warfare agent (CWA) dispersal, whether in the battlefield or after a terror act, is decontamination and rehabilitation of any contaminated area. Organophosphates (OPs) are considered to be among the deadliest CWAs to date. Other OPs are used as pesticides in modern agriculture, and are considered environmentally hazardous. Current methods for OP decontamination are either dangerous or insufficiently effective. As a promising solution for this problem, bioremediation--the use of biocomponents for environmental remediation--is a potentially effective, safe, and environment-friendly method. The technology relies on several enzymatic mechanisms, and can be applied in various ways. We will review recent achievements and potential applications, such as biocatalyst-containing foams and an enzymatic sponge, for environmental as well as personal exterior decontamination.

    更新日期:2019-11-01
  • Production of biodiesel using immobilized lipase--a critical review.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-12-04
    Kenthorai Raman Jegannathan,Sariah Abang,Denis Poncelet,Eng Seng Chan,Pogaku Ravindra

    Increase in volume of biodiesel production in the world scenario proves that biodiesel is accepted as an alternative to conventional fuel. Production of biodiesel using alkaline catalyst has been commercially implemented due to its high conversion and low production time. For the product and process development of biodiesel, enzymatic transesterification has been suggested to produce a high purity product with an economic, environment friendly process at mild reaction conditions. The enzyme cost being the main hurdle can be overcome by immobilization. Immobilized enzyme, which has been successfully used in various fields over the soluble counterpart, could be employed in biodiesel production with the aim of reducing the production cost by reusing the enzyme. This review attempts to provide an updated compilation of the studies reported on biodiesel production by using lipase immobilized through various techniques and the parameters, which affect their functionality.

    更新日期:2019-11-01
  • DNA-microarray technology: comparison of methodological factors of recent technique towards gene expression profiling.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-12-04
    Jai Prakash Muyal,Shiv K Singh,Heinz Fehrenbach

    DNA-microarray technology is a powerful tool to explore the potentials of functional genomics. Almost a decade back, it was not so easy to trace the molecular pathway process in the pathogenesis of diseases. Today DNA-microarray technology allows identifying candidate genes that are implicated in the development and progression of diseases. Because this technology is new, it remains a challenge to perform DNA-microarray experiments in the laboratory. All the technical factors associated with DNA-microarray experiments have a strong impact on the results and therefore, all parts/steps of the protocol, in particular sample preparation (i.e., RNA isolation, RNA preamplification, and cDNA labeling), hybridization, washing, and scanning settings need to be checked and optimized to obtain reliable results from DNA-microarray experiments.

    更新日期:2019-11-01
  • Protein function predictions based on the phylogenetic profile method.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-12-04
    Zhenran Jiang

    Inferring the functional relationships among proteins remains a challenging task in the post-genomics. With the increasing number of completed genomes and comparative genomics methods, application of phylogenetic profiles as a predictor of protein function has been proven to be a promising strategy for inferring the relationship of the proteins. This paper reviews important progress made in recent years towards understanding protein function by the application of the phylogenetic profile method. At the same time, some of the major challenges faced by protein function prediction are highlighted. The aim of this review is to emphasize the prospect of comparative genomic strategy that may be used to reach the important objective of protein function prediction. Furthermore, several important informatics resources currently available in this field are summarized. It is believed that these resources and methods can be utilized and integrated with other computational methods to provide valuable insight into elucidating the function of molecular networks.

    更新日期:2019-11-01
  • Statistical application and challenges in global gel-free proteomic analysis by mass spectrometry.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-11-26
    Lei Nie,Gang Wu,Weiwen Zhang

    Global gel-free proteomic analysis by mass spectrometry has been widely used as an important tool for exploring complex biological systems at the whole genome level. Simultaneous analysis of a large number of protein species is a complicated and challenging task. The challenges exist throughout all stages of a global gel-free proteomic analysis: experimental design, peptide/protein identification, data preprocessing and normalization, and inferential analysis. In addition to various efforts to improve the analytical technologies, statistical methodologies have been applied in all stages of proteomic analyses to help extract relevant information efficiently from large proteomic datasets. In this review, we summarize current applications of statistics in several stages of global gel-free proteomic analysis by mass spectrometry. We discuss the challenges associated with the applications of various statistical tools. Whenever possible, we also propose potential solutions on how to improve the data collection and interpretation for mass-spectrometry-based global proteomic analysis using more sophisticated and/or novel statistical approaches.

    更新日期:2019-11-01
  • Microbial biosynthesis and applications of gentamicin: a critical appraisal.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-10-22
    C Ganesh Kumar,M Himabindu,Annapurna Jetty

    Gentamicin is an aminoglycoside antibiotic produced by various species of the genus Micromonospora and has received much attention in the recent years as a broad-spectrum antibiotic for treatment of various infections. It exists as a complex of closely related aminoglycoside structures and the clinically significant one is the gentamicin C complex. This review article focuses attention on the present status of knowledge and the main advancements achieved in the last few decades on the subject of gentamicin with regard to its production, biosynthetic pathway, mode of action, and uses. The various nutritional and environmental parameters affecting gentamicin production and the factors affecting the release of bound gentamicin are discussed. Further, strain improvement using UV and/or chemical mutagenesis can be applied to augment the efficiency of the producer strain and a number of case studies are presented. Different detection and quantitative methods for gentamicin estimation and the mode of action of gentamicin are discussed in detail. This antibiotic finds extensive use in combination chemotherapy and as a drug for different delivery agents for treatment of osteomyelitis and other recent applications in gene therapy.

    更新日期:2019-11-01
  • Plant molecular farming: opportunities and challenges.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-10-22
    Pervin Basaran,Emilio Rodríguez-Cerezo

    Production of foreign molecules in transgenic plants is anticipated to be an alternative to already established, microbial or animal expression systems with lower production costs. This article reviews the different technologies and approaches currently used to produce economically interesting molecules in plants or plant cell cultures, to evaluate their technical feasibility and economic implications, and to assess the potential socioeconomic and environmental impacts deriving from the adoption of molecular farming products.

    更新日期:2019-11-01
  • Genetic engineering of cytokinins and their application to agriculture.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-10-16
    Qing-Hu Ma

    Cytokinins are master regulators of plant growth and development. They are involved in the regulation of many important physiological and metabolic processes. Recent progress in cytokinin research at the molecular level, including identification of related genes and cytokinin receptors, plus elucidation of signal transduction, has greatly increased our understanding of cytokinin actions. Although still in its infant stage, molecular breeding of crops with altered cytokinin metabolism, when combined with the transgenic approach, has shown very promising potential for application to agriculture. In this review we briefly introduce recent progress in cytokinin molecular biology, discuss applications of cytokinin genetic engineering to agriculture, and present implications and future research directions.

    更新日期:2019-11-01
  • Application of bacteriocins in the control of foodborne pathogenic and spoilage bacteria.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-06-24
    Antonio Galvez,Rosario Lucas Lopez,Hikmate Abriouel,Eva Valdivia,Nabil Ben Omar

    Bacteriocins are antimicrobial peptides or proteins produced by strains of diverse bacterial species. The antimicrobial activity of this group of natural substances against foodborne pathogenic, as well as spoilage bacteria, has raised considerable interest for their application in food preservation. Application of bacteriocins may help reduce the use of chemical preservatives and/or the intensity of heat and other physical treatments, satisfying the demands of consumers for foods that are fresh tasting, ready to eat, and lightly preserved. In recent years, considerable effort has been made to develop food applications for many different bacteriocins and bacteriocinogenic strains. Depending on the raw materials, processing conditions, distribution, and consumption, the different types of foods offer a great variety of scenarios where food poisoning, pathogenic, or spoilage bacteria may proliferate. Therefore, the effectiveness of bacteriocins requires careful testing in the food systems for which they are intended to be applied against the selected target bacteria. This and other issues on application of bacteriocins in foods of dairy, meat, seafood, and vegetable origins are addressed in this review.

    更新日期:2019-11-01
  • Biotechnological applications of acetic acid bacteria.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-06-24
    Peter Raspor,Dusan Goranovic

    The acetic acid bacteria (AAB) have important roles in food and beverage production, as well as in the bioproduction of industrial chemicals. In recent years, there have been major advances in understanding their taxonomy, molecular biology, and physiology, and in methods for their isolation and identification. AAB are obligate aerobes that oxidize sugars, sugar alcohols, and ethanol with the production of acetic acid as the major end product. This special type of metabolism differentiates them from all other bacteria. Recently, the AAB taxonomy has been strongly rearranged as new techniques using 16S rRNA sequence analysis have been introduced. Currently, the AAB are classified in ten genera in the family Acetobacteriaceae. AAB can not only play a positive role in the production of selected foods and beverages, but they can also spoil other foods and beverages. AAB occur in sugar- and alcohol-enriched environments. The difficulty of cultivation of AAB on semisolid media in the past resulted in poor knowledge of the species present in industrial processes. The first step of acetic acid production is the conversion of ethanol from a carbohydrate carried out by yeasts, and the second step is the oxidation of ethanol to acetic acid carried out by AAB. Vinegar is traditionally the product of acetous fermentation of natural alcoholic substrates. Depending on the substrate, vinegars can be classified as fruit, starch, or spirit substrate vinegars. Although a variety of bacteria can produce acetic acid, mostly members of Acetobacter, Gluconacetobacter, and Gluconobacter are used commercially. Industrial vinegar manufacturing processes fall into three main categories: slow processes, quick processes, and submerged processes. AAB also play an important role in cocoa production, which represents a significant means of income for some countries. Microbial cellulose, produced by AAB, possesses some excellent physical properties and has potential for many applications. Other products of biotransformations by AAB or their enzymes include 2-keto-L-gulonic acid, which is used for the production of vitamin C; D-tagatose, which is used as a bulking agent in food and a noncalorific sweetener; and shikimate, which is a key intermediate for a large number of antibiotics. Recently, for the first time, a pathogenic acetic acid bacterium was described, representing the newest and tenth genus of AAB.

    更新日期:2019-11-01
  • Production and characterization of gamma-polyglutamic acid nanoparticles for controlled anticancer drug release.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-06-24
    Bhavik Manocha,Argyrios Margaritis

    Gamma-polyglutamic acid (gamma-PGA) is a hydrophilic, biodegradable, and naturally available biopolymer produced by a number of microbial species, most commonly, the Bacillaceae family. Its biological properties such as nontoxicity, biocompatibility, and nonimmunogenicity qualify it as an important biomaterial in drug delivery applications. This review focuses mainly on the development of gamma-PGA nanoparticles as drug delivery carriers for anticancer therapeutics. We discuss various techniques for the production and characterization of gamma-PGA nanoparticles and controlled-release strategies. We also present a brief overview of the tumor physiology that forms the basis for the development of various targeted drug delivery approaches in cancer chemotherapy.

    更新日期:2019-11-01
  • Properties, potentials, and prospects of antifreeze proteins.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-03-07
    S Venketesh,C Dayananda

    Antifreeze proteins (AFPs) are a group of proteins that protect organisms from deep freezing temperatures and are expressed in vertebrates, invertebrates, plants, bacteria, and fungi. The nuclear magnetic resonance, x-ray structure, and many spectroscopic studies with AFPs have been instrumental in determining the structure-function relationship. Mutational studies have indicated the importance of hydrophobic residues in ice binding. Various studies have pointed out that the mechanism of AFP action is through its adsorption on the ice surface, which leads to a curved surface, preventing further growth of ice by the "Kelvin effect." The AFPs have potential industrial, medical, and agricultural application in different fields, such as food technology, preservation of cell lines, organs, cryosurgery, and cold hardy transgenic plants and animals. However, the applications of AFPs are marred by high cost due to low yield. This review deals with the source and properties of AFPs from an angle of their application and their potential. The possibility of production using different molecular biological techniques, which will help increase the yield, is also dealt with.

    更新日期:2019-11-01
  • Melon fruits: genetic diversity, physiology, and biotechnology features.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-03-07
    Hector G Nuñez-Palenius,Miguel Gomez-Lim,Neftali Ochoa-Alejo,Rebecca Grumet,Gene Lester,Daniel J Cantliffe

    Among Cucurbitaceae, Cucumis melo is one of the most important cultivated cucurbits. They are grown primarily for their fruit, which generally have a sweet aromatic flavor, with great diversity and size (50 g to 15 kg), flesh color (orange, green, white, and pink), rind color (green, yellow, white, orange, red, and gray), form (round, flat, and elongated), and dimension (4 to 200 cm). C. melo can be broken down into seven distinct types based on the previously discussed variations in the species. The melon fruits can be either climacteric or nonclimacteric, and as such, fruit can adhere to the stem or have an abscission layer where they will fall from the plant naturally at maturity. Traditional plant breeding of melons has been done for 100 years wherein plants were primarily developed as open-pollinated cultivars. More recently, in the past 30 years, melon improvement has been done by more traditional hybridization techniques. An improvement in germplasm is relatively slow and is limited by a restricted gene pool. Strong sexual incompatibility at the interspecific and intergeneric levels has restricted rapid development of new cultivars with high levels of disease resistance, insect resistance, flavor, and sweetness. In order to increase the rate and diversity of new traits in melon it would be advantageous to introduce new genes needed to enhance both melon productivity and melon fruit quality. This requires plant tissue and plant transformation techniques to introduce new or foreign genes into C. melo germplasm. In order to achieve a successful commercial application from biotechnology, a competent plant regeneration system of in vitro cultures for melon is required. More than 40 in vitro melon regeneration programs have been reported; however, regeneration of the various melon types has been highly variable and in some cases impossible. The reasons for this are still unknown, but this plays a heavy negative role on trying to use plant transformation technology to improve melon germplasm. In vitro manipulation of melon is difficult; genotypic responses to the culture method (i.e., organogenesis, somatic embryogenesis, etc.) as well as conditions for environmental and hormonal requirements for plant growth and regeneration continue to be poorly understood for developing simple in vitro procedures to culture and transform all C. melo genotypes. In many cases, this has to be done on an individual line basis. The present paper describes the various research findings related to successful approaches to plant regeneration and transgenic transformation of C. melo. It also describes potential improvement of melon to improve fruit quality characteristics and postharvest handling. Despite more than 140 transgenic melon field trials in the United States in 1996, there are still no commercial transgenic melon cultivars on the market. This may be a combination of technical or performance factors, intellectual property rights concerns, and, most likely, a lack of public acceptance. Regardless, the future for improvement of melon germplasm is bright when considering the knowledge base for both techniques and gene pools potentially useable for melon improvement.

    更新日期:2019-11-01
  • Apple pomace: a versatile substrate for biotechnological applications.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2008-03-07
    Francielo Vendruscolo,Patrícia M Albuquerque,Fernanda Streit,Elisa Esposito,Jorge L Ninow

    Apple pomace is the processing waste generated after apple juice manufacturing and represents up to 30% of the original fruit. This solid residue consists of a complex mixture of peel, core, seed, calyx, stem, and soft tissue. This residual material is a poor animal feed supplement because of its extremely low protein content and high amount of sugar. The application of agroindustrial by-products in bioprocesses offers a wide range of alternative substrates, thus helping solve pollution problems related to their disposal. Attempts have been made to use apple pomace to generate several value-added products, such as enzymes, single cell protein, aroma compounds, ethanol, organic acids, polysaccharides, and mushrooms. This article reviews recent developments regarding processes and products that employed apple pomace as a substrate for biotechnological applications.

    更新日期:2019-11-01
  • Guayule and Russian dandelion as alternative sources of natural rubber.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-12-19
    Jan B van Beilen,Yves Poirier

    Natural rubber, obtained almost exclusively from the Para rubber tree (Hevea brasiliensis), is a unique biopolymer of strategic importance that, in many of its most significant applications, cannot be replaced by synthetic rubber alternatives. Several pressing motives lead to the search for alternative sources of natural rubber. These include increased evidence of allergenic reactions to Hevea rubber, the danger that the fungal pathogen Microcyclus ulei, causative agent of South American Leaf Blight (SALB), might spread to Southeast Asia, which would severely disrupt rubber production, potential shortages of supply due to increasing demand and changes in land use, and a general trend towards the replacement of petroleum-derived chemicals with renewables. Two plant species have received considerable attention as potential alternative sources of natural rubber: the Mexican shrub Guayule (Parthenium argentatum Gray) and the Russian dandelion (Taraxacum koksaghyz). This review will summarize the current production methods and applications of natural rubber (dry rubber and latex), the threats to the production of natural rubber from the rubber tree, and describe the current knowledge of the production of natural rubber from guayule and Russian dandelion.

    更新日期:2019-11-01
  • Microbial mannanases: an overview of production and applications.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-12-19
    Samriti Dhawan,Jagdeep Kaur

    Microbial mannanases have become biotechnologically important since they target the hydrolysis of complex polysaccharides of plant tissues into simple molecules like manno-oligosaccharides and mannoses. The role of mannanases in the paper and pulp industry is well established and recently they have found application in the food and feed technology, coffee extraction, oil drilling and detergent industry. Mannanses are enzymes produced mainly from microorganisms but mannanases produced from plants and animals have also been reported. Bacterial mannanases are mostly extracellular and can act in a wide range of pH and temperature, though acidic and neutral mannanases are more common. This review will focus on complex mannan structure and the microbial enzyme complex involved in its complete breakdown, mannanase sources, production conditions and their applications in the commercial sector. The reference to plant and animal mannanases has been made to complete the overview. However, the major emphasis of the review is on the microbial mannanases.

    更新日期:2019-11-01
  • Effects of water on enzyme performance with an emphasis on the reactions in supercritical fluids.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-12-19
    K Rezaei,E Jenab,F Temelli

    Enzymes require a certain level of water in their structures in order to maintain their natural conformation, allowing them to deliver their full functionality. Furthermore, as a modifier of the solvent, up to a certain level, water can modify the solvent properties such as polarity/polarizability as well as the solubility of the reactants and the products. In addition, depending on the type of the reaction, water can be a substrate (e.g., in hydrolysis) or a product (e.g., in esterolysis) of the enzymatic reaction, influencing the enzyme turnover in different ways. It is found that regardless of the type of reaction, the functionality of enzyme itself is maximum at an optimum level of water, beyond which the enzyme performance is declined due to the loss in enzyme stability. Furthermore, mass transfer limitations caused by pathway blockage and/or by reduced solubilities of the reactants and/or products can also affect the enzyme performance at higher water levels. Controlling water content of ingoing CO2 and substrates as well as precise management of enzyme support and salt hydrates are important strategies to adjust water level in reaction media, especially in supercritical environments.

    更新日期:2019-11-01
  • Metabolic engineering of plant L-ascorbic acid biosynthesis: recent trends and applications.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-09-13
    Lei Zhang,Zinan Wang,Yang Xia,Guoyin Kai,Wansheng Chen,Kexuan Tang

    Vitamin C (L-ascorbic acid; AsA) is the major soluble antioxidant found in plants and is also an essential component of human nutrition. Although numerous biotechnological methods have been exploited to increase its yield, pressures such as commercial competition and environmental concerns make it urgent to find a new way for industrial production of plant-derived AsA. Engineering plant AsA has now become feasible because of our increased understanding of its biosynthetic pathway. Several possible strategies could be followed to increase AsA production, such as overcoming the rate limiting steps in the biosynthetic pathway, promoting recycling, and reducing catabolism. For these purposes, genes of plant, microbial and animal origins have been successfully used. Several examples will be given to illustrate these various approaches. The existing and potential achievements in increasing AsA production would provide the opportunity for enhancing nutritional quality and stress tolerance of crop plants.

    更新日期:2019-11-01
  • The genus Gluconobacter oxydans: comprehensive overview of biochemistry and biotechnological applications.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-09-13
    Cassandra De Muynck,Catarina S S Pereira,Myriam Naessens,Sofie Parmentier,Wim Soetaert,Erick J Vandamme

    The genus Gluconobacter comprises some of the most frequently used microorganisms when it comes to biotechnological applications. Not only has it been involved in "historical" production processes, such as vinegar production, but in the last decades many bioconversion routes for special and rare sugars involving Gluconobacter have been developed. Among the most recent are the biotransformations involved in the production of L-ribose and miglitol, both very promising pharmaceutical lead molecules. Most of these processes make use of Gluconobacter's membrane-bound polyol dehydrogenases. However, recently other enzymes have also caught the eye of industrial biotechnology. Among them are dextran dextrinase, capable of transglucosylating substrate molecules, and intracellular NAD-dependent polyol dehydrogenases, of interest for co-enzyme regeneration. As such, Gluconobacter is an important industrial microbial strain, but it also finds use in other fields of biotechnology, such as biosensor-technology. This review aims to give an overview of the myriad of applications for Gluconobacter, with a special focus on some recent developments.

    更新日期:2019-11-01
  • The state of the art in the production of fructose from inulin enzymatic hydrolysis.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-09-13
    Emanuele Ricca,Vincenza Calabrò,Stefano Curcio,Gabriele Iorio

    The present work reviews the main advancements achieved in the last decades in the study of the fructose production process by inulin enzymatic hydrolysis. With the aim of collecting and clarifying the majority of the knowledge in this area, the research on this subject has been divided in three main parts: a) the characteristics of inulin (the process reactant); b) the properties of the enzyme inulinase and its hydrolytic action; c) the advances in the study of the applications of inulinases in bioreactors for fructose production. Many vegetable sources of inulin are reported, including information about their yields in terms of inulin. The properties of inulin that appear relevant for the process are also summarized, with reference to their vegetable origin. The characteristics of the inulinase enzyme that catalyzes inulin hydrolysis, together with the most relevant information for a correct process design and implementation, are described in the paper. An extended collection of data on microorganisms capable of producing inulinase is reported. The following characteristics and properties of inulinase are highlighted: molecular weight, mode of action, activity and stability with respect to changes in temperature and pH, kinetic behavior and effect of inhibitors. The paper describes in detail the main aspects of the enzyme hydrolysis reaction; in particular, how enzyme and reactant properties can affect process performance. The properties of inulinase immobilized on various supports are shown and compared to those of the enzyme in its native state. Finally, a number of applications of free and immobilized inulinases and whole cells in bioreactors are reported, showing the different operating procedures and reactor types adopted for fructose production from inulin on a laboratory scale.

    更新日期:2019-11-01
  • Novel delivery systems for interferons.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-09-13
    Mehrdad Hamidi,Abdolhossein Zarrin,Mahshid Foroozesh

    Interferons, IFNs, are among the most widely studied and clinically used biopharmaceuticals. Despite their invaluable therapeutic roles, the widespread use of IFNs suffers from some inherent limitations, mainly their relatively short circulation lifespan and their unwanted effects on some non-target tissues. Therefore, both these constraints have become the central focus points for the research efforts on the development of a variety of novel delivery systems for these therapeutic agents with the ultimate goal of improving their therapeutic end-points. Generally, the delivery systems currently under investigation for IFNs can be classified as particulate delivery systems, including micro- and nano-particles, liposomes, minipellets, cellular carriers, and non-particulate delivery systems, including PEGylated IFNs, other chemically conjugated IFNs, immunoconjugated IFNs, and genetically conjugated IFNs. All these strategies and techniques have their own possibilities and limitations, which should be taken into account when considering their clinical application. In this article, currently studied delivery systems/techniques for IFN delivery have been reviewed extensively, with the main focus on the pharmacokinetic consequences of each procedure.

    更新日期:2019-11-01
  • Yeast phytases: present scenario and future perspectives.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-06-21
    Parvinder Kaur,G Kunze,T Satyanarayana

    Phytases hydrolyze phytates to liberate soluble and thus readily utilizable inorganic phosphate. Although phytases are produced by various groups of microbes, yeasts being simple eukaryotes and mostly non-pathogenic with proven probiotic benefits can serve as ideal candidates for phytase research. The full potential of yeast phytases has not, however, been exploited. This review focuses attention on the present status of knowledge on the production, characterization, molecular characteristics, and cloning and over-expression of yeast phytases. Several potential applications of the yeast phytases in feeds and foods, and in the synthesis of lower myo-inositol phosphates are also discussed.

    更新日期:2019-11-01
  • Molecular phylogenies and evolution of crt genes in algae.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-06-21
    Qian Chen,Jian-Guo Jiang,Fei Wang

    The carotenoids constitute the most widespread class of pigments in nature. Most previous work has concentrated on the identification and characterization of their chemical physical properties and bioavailability. In recent years, significant amounts of research have been conducted in an attempt to analyze the genes and the molecular regulation of the genes involved in the biosynthesis of carotenoids. However, it is important not to lose sight of the early evolution of carotenoid biosynthesis. One of the major obstacles in understanding the evolution of the respective enzymes and their patterns of selection is a lack of a well-supported phylogenic analysis. In the present research, a major long-term objective was to provide a clearer picture of the evolutionary history of genes, together with an evaluation of the patterns of selection in algae. These phylogenies will be important in studies characterizing the evolution of algae. The gene sequences of the enzymes involved in the major steps of the carotenoid biosynthetic pathway in algae (cyanobacteria, rhofophyta, chlorophyta) have been analyzed. Phylogenetic relationships among protein-coding DNA sequences were reconstructed by neighbor-joining (NJ) analysis for the respective carotenoid biosynthetic pathway genes (crt) in algae. The analysis also contains an estimation of the rate of nonsynonymous nucleotide substitutions per nonsynonymous site (d(N)), synonymous nucleotide substitution per synonymous site (d(S)), and the ratio of nonsynonmous (d(N)/d(S)) for the test of selection patterns. The phylogenetic trees show that the taxa of some genera have a closer evolutionary relationship with other genera in some gene sequences, which suggests a common ancient origin and that lateral gene transfer has occurred among unrelated genera. The d(N) values of crt genes in the early pathway are relatively low, while those of the following steps are slightly higher, while the d(N) values of crt genes in chlorophyta are higher than those in cyanobacteria. Most of the d(N)/d(S) values exceed 1. The phylogenetic analysis revealed that lateral gene transfer may have taken place across algal genomes and the d(N) values suggest that most of the early crt genes are well conserved compared to the later crt genes. Furthermore, d(N) values also revealed that the crt genes of chlorophyta are more evolutionary than cyanobacteria. The amino acids' changes are mostly adaptive evolution under the influence of positive diversity selection.

    更新日期:2019-11-01
  • Integrative analysis of transcriptomic and proteomic data: challenges, solutions and applications.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-06-21
    Lei Nie,Gang Wu,David E Culley,Johannes C M Scholten,Weiwen Zhang

    Recent advances in high-throughput technologies enable quantitative monitoring of the abundance of various biological molecules and allow determination of their variation between biological states on a genomic scale. Two popular platforms are DNA microarrays that measure messenger RNA transcript levels, and gel-free proteomic analyses that quantify protein abundance. Obviously, no single approach can fully unravel the complexities of fundamental biology and it is equally clear that integrative analysis of multiple levels of gene expression would be valuable in this endeavor. However, most integrative transcriptomic and proteomic studies have thus far either failed to find a correlation or only observed a weak correlation. In addition to various biological factors, it is suggested that the poor correlation could be quite possibly due to the inadequacy of available statistical tools to compensate for biases in the data collection methodologies. To address this issue, attempts have recently been made to systematically investigate the correlation patterns between transcriptomic and proteomic datasets, and to develop sophisticated statistical tools to improve the chances of capturing a relationship. The goal of these efforts is to enhance understanding of the relationship between transcriptomes and proteomes so that integrative analyses may be utilized to reveal new biological insights that are not accessible through one-dimensional datasets. In this review, we outline some of the challenges associated with integrative analyses and present some preliminary statistical solutions. In addition, some new applications of integrated transcriptomic and proteomic analysis to the investigation of post-transcriptional regulation are also discussed.

    更新日期:2019-11-01
  • L-asparaginase: a promising chemotherapeutic agent.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-03-17
    Neelam Verma,Kuldeep Kumar,Gurnoor Kaur,Sneh Anand

    This article comprises detailed information about L-asparaginase, encompassing topics such as microbial and plant sources of L-asparaginase, treatment with L-asparaginase, mechanism of action of L-asparaginase, production, purification, properties, expression and characteristics of l-asparaginase along with information about studies on the structure of L-asparaginase. Although L-asparaginase has been reviewed by Savitri and Azmi (2003), our effort has been to include recent and updated information about the enzyme covering new aspects such as structural modification and immobilization of L-asparaginase, recombinant L-asparaginase, resistance to L-asparaginase, methods of assay of L-asparagine and L-asparaginase activity using the biosensor approach, L-asparaginase activity in soil and the factors affecting it. Also, side-effects of L-asparaginase treatment in acute lymphoblastic leukemia (ALL) have been discussed in the current review. L-asparaginase has been and is still one of the most widely studied therapeutic enzymes by researchers and scientists worldwide.

    更新日期:2019-11-01
  • Hairy root culture for mass-production of high-value secondary metabolites.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-03-17
    Smita Srivastava,Ashok K Srivastava

    Plant cell cultivations are being considered as an alternative to agricultural processes for producing valuable phytochemicals. Since many of these products (secondary metabolites) are obtained by direct extraction from plants grown in natural habitat, several factors can alter their yield. The use of plant cell cultures has overcome several inconveniences for the production of these secondary metabolites. Organized cultures, and especially root cultures, can make a significant contribution in the production of secondary metabolites. Most of the research efforts that use differentiated cultures instead of cell suspension cultures have focused on transformed (hairy) roots. Agrobacterium rhizogenes causes hairy root disease in plants. The neoplastic (cancerous) roots produced by A. rhizogenes infection are characterized by high growth rate, genetic stability and growth in hormone free media. These genetically transformed root cultures can produce levels of secondary metabolites comparable to that of intact plants. Hairy root cultures offer promise for high production and productivity of valuable secondary metabolites (used as pharmaceuticals, pigments and flavors) in many plants. The main constraint for commercial exploitation of hairy root cultivations is the development and scaling up of appropriate reactor vessels (bioreactors) that permit the growth of interconnected tissues normally unevenly distributed throughout the vessel. Emphasis has focused on designing appropriate bioreactors suitable to culture the delicate and sensitive plant hairy roots. Recent reactors used for mass production of hairy roots can roughly be divided as liquid-phase, gas-phase, or hybrid reactors. The present review highlights the nature, applications, perspectives and scale up of hairy root cultures for the production of valuable secondary metabolites.

    更新日期:2019-11-01
  • Bacterial chitinases: properties and potential.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-03-17
    Debaditya Bhattacharya,Anand Nagpure,Rajinder K Gupta

    Chitin is among the most abundant biomass present on Earth. Chitinase plays an important role in the decomposition of chitin and potentially in the utilization of chitin as a renewable resource. During the previous decade, chitinases have received increased attention because of their wide range of applications. Chito-oligomers produced by enzymatic hydrolysis of chitin have been of interest in recent years due to their broad applications in medical, agricultural, and industrial applications, including antibacterial, antifungal, hypocholesterolemic, and antihypertensive activity, and as a food quality enhancer. Microorganisms, particularly bacteria, form one of the major sources of chitinase. In this article, we have reviewed some of the chitinases produced by bacterial systems that have gained worldwide research interest for their diverse properties and potential industrial uses.

    更新日期:2019-11-01
  • Microbial biosynthesis of polyglutamic acid biopolymer and applications in the biopharmaceutical, biomedical and food industries.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2007-03-17
    Joerg M Buescher,Argyrios Margaritis

    This review article provides an updated critical literature review on the production and applications of Polyglutamic Acid (PGA). alpha-PGA is synthesized chemically, whereas gamma-PGA can be produced by a number of microbial species, most prominently various Bacilli. Great insight into the microbial formation of gamma-PGA has been gained thanks to the development of molecular biological techniques. Moreover, there is a great variety of applications for both isoforms of PGA, many of which have not been discovered until recently. These applications include: wastewater treatment, food products, drug delivery, medical adhesives, vaccines, PGA nanoparticles for on-site drug release in cancer chemotherapy, and tissue engineering.

    更新日期:2019-11-01
  • Bio-microarray fabrication techniques--a review.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2006-11-11
    Irena Barbulovic-Nad,Michael Lucente,Yu Sun,Mingjun Zhang,Aaron R Wheeler,Markus Bussmann

    Microarrays with biomolecules (e.g., DNA and proteins), cells, and tissues immobilized on solid substrates are important tools for biological research, including genomics, proteomics, and cell analysis. In this paper, the current state of microarray fabrication is reviewed. According to spot formation techniques, methods are categorized as "contact printing" and "non-contact printing." Contact printing is a widely used technology, comprising methods such as contact pin printing and microstamping. These methods have many advantages, including reproducibility of printed spots and facile maintenance, as well as drawbacks, including low-throughput fabrication of arrays. Non-contact printing techniques are newer and more varied, comprising photochemistry-based methods, laser writing, electrospray deposition, and inkjet technologies. These technologies emerged from other applications and have the potential to increase microarray fabrication throughput; however, there are several challenges in applying them to microarray fabrication, including interference from satellite drops and biomolecule denaturization.

    更新日期:2019-11-01
  • Biosorption with algae: a statistical review.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2006-11-11
    E Romera,F González,A Ballester,M L Blázquez,J A Muñoz

    The state of the art in the field of biosorption using algae as biomass is reviewed. The available data of maximum sorption uptake (qmax) and biomass-metal affinity (b) for Cd2 +, Cu2 +, Ni2 +, Pb2 + and Zn2 + were statistically analyzed using 37 different algae (20 brown algae, 9 red algae and 8 green algae). Metal biosorption research with algae has used mainly brown algae in pursuit of treatments, which improve its sorption uptake. The information available in connection with multimetallic systems is very poor. Values of qmax were close to 1 mmol/g for copper and lead and smaller for the other metals. Metal recovery performance was worse for nickel and zinc, but the number of samples for zinc was very small. All the metals except lead present a similar affinity for brown algae. The difference in the behavior of lead may be due to a different uptake mechanism. Brown algae stand out as very good biosorbents of heavy metals. The best performer for metal biosorption is lead.

    更新日期:2019-11-01
  • Potential applications of the oxidoreductive enzymes in the decolorization and detoxification of textile and other synthetic dyes from polluted water: a review.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2006-11-11
    Qayyum Husain

    Recently, the enzymatic approach has attracted much interest in the decolorization/degradation of textile and other industrially important dyes from wastewater as an alternative strategy to conventional chemical, physical and biological treatments, which pose serious limitations. Enzymatic treatment is very useful due to the action of enzymes on pollutants even when they are present in very dilute solutions and recalcitrant to the action of various microbes participating in the degradation of dyes. The potential of the enzymes (peroxidases, manganese peroxidases, lignin peroxidases, laccases, microperoxidase-11, polyphenol oxidases, and azoreductases) has been exploited in the decolorization and degradation of dyes. Some of the recalcitrant dyes were not degraded/decolorized in the presence of such enzymes. The addition of certain redox mediators enhanced the range of substrates and efficiency of degradation of the recalcitrant compounds. Several redox mediators have been reported in the literature, but very few of them are frequently used (e.g., 1-hydroxybenzotriazole, veratryl alcohol, violuric acid, 2-methoxy-phenothiazone). Soluble enzymes cannot be exploited at the large scale due to limitations such as stability and reusability. Therefore, the use of immobilized enzymes has significant advantages over soluble enzymes. In the near future, technology based on the enzymatic treatment of dyes present in the industrial effluents/wastewater will play a vital role. Treatment of wastewater on a large scale will also be possible by using reactors containing immobilized enzymes.

    更新日期:2019-11-01
  • Directed evolution: an approach to engineer enzymes.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2006-08-23
    Jasjeet Kaur,Rohit Sharma

    Directed evolution is being used increasingly in industrial and academic laboratories to modify and improve commercially important enzymes. Laboratory evolution is thought to make its biggest contribution in explorations of non-natural functions, by allowing us to distinguish the properties nurtured by evolution. In this review we report the significant advances achieved with respect to the methods of biocatalyst improvement and some critical properties and applications of the modified enzymes. The application of directed evolution has been elaborately demonstrated for protein solubility, stability and catalytic efficiency. Modification of certain enzymes for their application in enantioselective catalysis has also been elucidated. By providing a simple and reliable route to enzyme improvement, directed evolution has emerged as a key technology for enzyme engineering and biocatalysis.

    更新日期:2019-11-01
  • Use of genetically engineered microorganisms (GEMs) for the bioremediation of contaminants.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2006-08-23
    Meltem Urgun-Demirtas,Benjamin Stark,Krishna Pagilla

    This paper presents a critical review of the literature on the application of genetically engineered microorganisms (GEMs) in bioremediation. The important aspects of using GEMs in bioremediation, such as development of novel strains with desirable properties through pathway construction and the modification of enzyme specificity and affinity, are discussed in detail. Particular attention is given to the genetic engineering of bacteria using bacterial hemoglobin (VHb) for the treatment of aromatic organic compounds under hypoxic conditions. The application of VHb technology may advance treatment of contaminated sites, where oxygen availability limits the growth of aerobic bioremediating bacteria, as well as the functioning of oxygenases required for mineralization of many organic pollutants. Despite the many advantages of GEMs, there are still concerns that their introduction into polluted sites to enhance bioremediation may have adverse environmental effects, such as gene transfer. The extent of horizontal gene transfer from GEMs in the environment, compared to that of native organisms including benefits regarding bacterial bioremediation that may occur as a result of such transfer, is discussed. Recent advances in tracking methods and containment strategies for GEMs, including several biological systems that have been developed to detect the fate of GEMs in the environment, are also summarized in this review. Critical research questions pertaining to the development and implementation of GEMs for enhanced bioremediation have been identified and posed for possible future research.

    更新日期:2019-11-01
  • Biotechnological methods to accelerate cheddar cheese ripening.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2006-08-23
    Sorayya Azarnia,Normand Robert,Byong Lee

    Cheese is one of the dairy products that can result from the enzymatic coagulation of milk. The basic steps of the transformation of milk into cheese are coagulation, draining, and ripening. Ripening is the complex process required for the development of a cheese's flavor, texture and aroma. Proteolysis, lipolysis and glycolysis are the three main biochemical reactions that are responsible for the basic changes during the maturation period. As ripening is a relatively expensive process for the cheese industry, reducing maturation time without destroying the quality of the ripened cheese has economic and technological benefits. Elevated ripening temperatures, addition of enzymes, addition of cheese slurry, attenuated starters, adjunct cultures, genetically engineered starters and recombinant enzymes and microencapsulation of ripening enzymes are traditional and modern methods used to accelerate cheese ripening. In this context, an up to date review of Cheddar cheese ripening is presented.

    更新日期:2019-11-01
  • Enzymatic modifications of cephalosporins by cephalosporin acylase and other enzymes.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2006-07-01
    Vijay Chintaman Sonawane

    Semisynthetic cephalosporins are important antibacterials in clinical practice. Semisynthetic cephalosporins are manufactured by derivatizing 7-aminocephalosporanic acid (7-ACA) and its desacetylated form. Microbial enzymes such as D-amino acid oxidase, glutaryl-7-ACA acylase and cephalosporin esterase are being used as biocatalysts for the conversion of cephalosporin C (CEPH-C) to 7-ACA and its desacetylated derivatives. Recent developments in the field of enzymatic modifications of cephalosporin with special emphasis on group of enzymes called as cephalosporin acylase is discussed in this review. Aspects related to screening methods, isolation and purification, immobilization, molecular cloning, gene structure and expression and protein engineering of cephalosporin acylases have been covered. Topics pertaining to enzymatic modifications of cephalosporin by D-amino acid oxidase, cephalosporin methoxylase and beta-lactamase are also covered.

    更新日期:2019-11-01
  • Polyunsaturated fatty acids: biotechnology.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2006-07-01
    Dnyaneshwar Warude,Kalpana Joshi,Abhay Harsulkar

    Polyunsaturated fatty acids like EPA and DHA have attracted a great attention due to their beneficial effects on human health. At present, fish oil is the major source of EPA and DHA. Various alternative sources are being explored to get these essential fatty acids. Genes encoding enzymes involved in the biosyntheses of PUFAs have been identified, cloned and gene prospecting becomes a novel method for enhanced PUFA production. Desaturase and elongase genes have important biotechnological appeal from genetic engineering point of view. This review highlights the research and results on such enzymes.

    更新日期:2019-11-01
  • Involvement of nitrogen-containing compounds in beta-lactam biosynthesis and its control.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2006-07-01
    Arnold L Demain,Preeti Vaishnav

    Biosynthesis of beta-lactam antibiotics by fungi and actinomycetes is markedly affected by compounds containing nitrogen. The different processes employed by the spectrum of microbes capable of making these valuable compounds are affected differently by particular compounds. Ammonium ions, except at very low concentrations, exert negative effects via nitrogen metabolite repression, sometimes involving the nitrogen regulatory gene nre. Certain amino acids are precursors or inducers, whereas others are involved in repression and, in certain cases, as inhibitors of biosynthetic enzymes and of enzymes supplying precursors. The most important amino acids from the viewpoint of regulation are lysine, methionine, glutamate and valine. Surprisingly, diamines such as diaminopropane, putrescine and cadaverine induce cephamycin production by actinomycetes. In addition to penicillins and cephalosporins made by fungi and cephamycins made by actinomycetes, other beta-lactams are made by actinomycetes and unicellular bacteria. These include clavams (e.g., clavulanic acid), carbapenems (e.g., thienamycin), nocardicins and monobactams. Here also, amino acids are precursors and inhibitors, but only little is known about regulation. In the case of the simplest carbapenem made by unicellular bacteria, i.e., 1-carba-2-em-3-carboxylic acid, quorum sensors containing homoserine lactone are inducers.

    更新日期:2019-11-01
  • Microbial CO conversions with applications in synthesis gas purification and bio-desulfurization.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2006-04-06
    Jan Sipma,Anne M Henstra,Sofiya M Parshina,Piet N Lens,Gatze Lettinga,Alfons J M Stams

    Recent advances in the field of microbial physiology demonstrate that carbon monoxide is a readily used substrate by a wide variety of anaerobic micro-organisms, and may be employed in novel biotechnological processes for production of bulk and fine chemicals or in biological treatment of waste streams. Synthesis gas produced from fossil fuels or biomass is rich in hydrogen and carbon monoxide. Conversion of carbon monoxide to hydrogen allows use of synthesis gas in existing hydrogen utilizing processes and is interesting in view of a transition from hydrogen production from fossil fuels to sustainable (CO2-neutral) biomass. The conversion of CO with H2O to CO2 and H2 is catalyzed by a rapidly increasing group of micro-organisms. Hydrogen is a preferred electron donor in biotechnological desulfurization ofwastewaters and flue gases. Additionally, CO is a good alternative electron donor considering the recent isolation of a CO oxidizing, sulfate reducing bacterium. Here we review CO utilization by various anaerobic micro-organisms and their possible role in biotechnological processes, with a focus on hydrogen production and bio-desulfurization.

    更新日期:2019-11-01
  • Near infrared spectroscopy for bioprocess monitoring and control: current status and future trends.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2006-04-06
    Matthew Scarff,S Alison Arnold,Linda M Harvey,Brian McNeil

    The development of Near Infrared Spectroscopy has paralleled that of the PC, and the application of NIR in many industries has undergone explosive growth in recent years. This has been particularly apparent in the area of microbial and cell culture system monitoring and control. Potentially, NIR offers the prospect of real-time control of the physiology of cultured cells in fermenters, leading to marked improvements in authenticity, purity and production efficiency. Despite this, NIR is not yet as widely applied within the bioprocessing industry as its potential might suggest. This review critically evaluates the development of this rapidly moving area as it pertains to microbial and cell culture system control and highlights the critical stages in the development of the technology. It indicates the work that must still be carried out if the full potential of NIR is to be exploited in making proteins, hormones and antibiotics by the fermentation route. The review comes at a particularly timely moment when NIR stands on the threshold of widespread acceptance in bioprocessing. This is the ideal moment to assess what the technology can offer the microbiologist, and where it may develop in the future.

    更新日期:2019-11-01
  • Composting: a potentially safe process for disposal of genetically modified organisms.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2006-04-06
    Ajay Singh,Kate Billingsley,Owen Ward

    The widespread use of genetically modified organisms (GMOs) may result in the release of GMOs into the environment. The potential risks regarding their use and implementation of disposal methods, especially the possibility of novel genes from GMOs being transferred to natural organisms, need to be evaluated and better understood. There is an increasingly accepted public view that GMO products introduced into the environment should be degradable and should disappear after a limited period of time. Due to the risk of possible horizontal gene transfer, disposal methods for GMOs need to address destruction of both the organism and the genetic material. During the last two decades, we have developed a greater understanding of the biochemical, microbiological and molecular concepts of the composting process, such that maximum decomposition may be achieved in the shortest time with minimal negative impacts to the environment. The conditions created in a properly managed composting process environment may help in destroying GMOs and their genes, thereby reducing the risk of the spread of genetic material. When considering composting as a potential method for the disposal of GMOs, the establishment of controlled conditions providing an essentially homogenous environment appears to be an important requirement. An evaluation of composting as a safe option for disposal of GMOs is provided in this review.

    更新日期:2019-11-01
  • A review of plastic waste biodegradation.
    Crit. Rev. Biotechnol. (IF 7.054) Pub Date : 2006-01-20
    Ying Zheng,Ernest K Yanful,Amarjeet S Bassi

    With more and more plastics being employed in human lives and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years. This review looks at the technological advancement made in the development of more easily biodegradable plastics and the biodegradation of conventional plastics by microorganisms. Additives, such as pro-oxidants and starch, are applied in synthetic materials to modify and make plastics biodegradable. Recent research has shown that thermoplastics derived from polyolefins, traditionally considered resistant to biodegradation in ambient environment, are biodegraded following photo-degradation and chemical degradation. Thermoset plastics, such as aliphatic polyester and polyester polyurethane, are easily attacked by microorganisms directly because of the potential hydrolytic cleavage of ester or urethane bonds in their structures. Some microorganisms have been isolated to utilize polyurethane as a sole source of carbon and nitrogen source. Aliphatic-aromatic copolyesters have active commercial applications because of their good mechanical properties and biodegradability. Reviewing published and ongoing studies on plastic biodegradation, this paper attempts to make conclusions on potentially viable methods to reduce impacts of plastic waste on the environment.

    更新日期:2019-11-01
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