ABSTRACT: The frequency of water exchange and reducing the risk of eutrophication to surrounding water bodies have always been water-quality control issues in recirculating aquaculture systems. In this study, maize straw biochar prepared through pyrolysis showed great potential for both bacterial immobilization and pollutant adsorption. Heterotrophic bacterial strains of Sphingomonas sp. PDD-57b-25 and Acinetobacter towneri were isolated in situ from wastewater for pollutant remediation through a 16S rDNA-based method, which has been rarely reported to date. The selected strains had higher ammonia nitrogen (NH₄⁺-N, 63%), nitrite nitrogen (NO₂^--N, 38%), nitrate nitrogen (NO₃^--N, 25%) and total phosphorus (TP, 35%) assimilation capacities than those of other widely applied bacteria under similar medium conditions. In addition, more NH₄⁺-N (+16%), NO₂^--N (+14%), NO₃^--N (+17%) and TP (+19%) was removed by biochar-immobilized isolated strains than dissociated strains, suggesting their use may provide a means of improving water-quality control in recirculating aquaculture. With specific additions (4 g l^-1) of biochar-immobilized Sphingomonas sp. PDD-57b-25 and A. towneri, the dissolved inorganic nitrogen (approximately 0.45 mg l^-1) and TP (approximately 0.09 mg l^-1) levels were maintained below the clean water threshold for recirculating aquaculture of crab Eriocheir sinensis. Furthermore, the added strains exhibited high bio-safety and were capable of improving the yield and quality of crabs. Results indicate the potential applicability of biochar-immobilized Sphingomonas sp. PDD-57b-25 and A. towneri in agricultural sewage treatments. Further, the experimental methodology developed here may be used for the exploration of new strains for practical aquaculture.

中文翻译：

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生物炭固定的鞘氨醇单胞菌 和不动杆菌属。分离物可增强营养去除：在蟹类水产养殖中的潜在应用

摘要：换水的频率和减少对周围水体富营养化的风险一直是循环水产养殖系统中水质控制的问题。在这项研究中，通过热解制备的玉米秸秆生物炭显示出巨大的潜力，可以固定细菌和吸附污染物。Sphingomonas sp。的异养细菌菌株。通过基于16S rDNA的方法从废水中原位分离PDD-57b-25和不动杆菌，以修复污染物，迄今为止尚未见报道。所选菌株具有较高的氨氮（NH ₄ ⁺ -N，63％），亚硝酸盐氮（NO ₂ ^-- N，38％），硝酸盐氮（NO₃ ^-- N，25％）和总磷（TP，35％）的同化能力比其他广泛应用的细菌在相似的培养基条件下要高。此外，通过固定生物炭的方法分离了更多的NH ₄ ⁺ -N（+16％），NO ₂ ^-- N（+14％），NO ₃ ^-- N（+ 17％）和TP（+ 19％）。与分离的菌株相比，这表明它们的使用可能提供改善循环水产养殖中水质控制的手段。与特定添加（4 gl ^-1）生物炭固定的鞘氨醇单胞菌sp。PDD-57b-25和A.towneri，溶解的无机氮（约0.45 mg l ^-1）和TP（约0.09 mg l^-1）的水平保持在清洁水阈值以下以进行中华绒螯蟹的循环水产养殖。此外，添加的菌株显示出高的生物安全性，并且能够提高螃蟹的产量和质量。结果表明生物炭固定的鞘氨醇单胞菌sp的潜在适用性。PDD-57b-25和A. towneri用于农业污水处理。此外，此处开发的实验方法可用于探索用于实际水产养殖的新菌株。