arsenite-oxidizing bacteria in activated sludge Raw sequence reads

Biological As(III) oxidation is a key step to remove the toxic As(III) from contaminated water. The capability of As(III) oxidation and the microbial community responsible for this process in wastewater treatment facilities, however, is not well documented. In this study, two groups of lab-scale bioreactors were operated to investigate the capability of biological As(III) oxidation by treating As(III)-containing wastewater. It is indicated that As(III) oxidation could occur under anoxic and oxic conditions. The kinetic model suggested that the rate of oxic As(III) oxidation was higher than anoxic condition. Microcosm experiments further indicated that the biological As(III) oxidation process could be driven by microorganisms using the nitrate or oxygen as the available electron acceptors, suggesting the potentials of this process in wastewater treatment facilities. In addition, DNA based stable isotope probing (DNA-SIP) was performed to identify the putative chemoautotrophic As(III)-oxidizing bacteria (AOBs) inhabiting the activated sludge. Bacteria associated with Hydrogenophaga were identified as an aerobic AOB,while Thiobacillus were identified as a nitrate-dependent AOB. Moreover, metagenomic binning reconstructed a number of high-quality metagenome-assembled genomes (MAGs) associated with putative AOBs. Function genes encoding the As resistance, As(III) oxidation, denitrification, and carbon fixation were identified in these AOBs-associated MAGs, suggesting their potentials of anoxic and/or oxic chemoautotrophic As(III) oxidation. In addition, the detection of genes encoding the secondary metabolite biosynthesis and extracellular polymeric substances metabolisms in these MAGs may facilitate the thrive of putative AOBs and enhance their capability for As(III) oxidation.

生物三价砷（As(III)）氧化是从受污染水体中去除有毒三价砷的关键环节。然而，当前针对污水处理设施中三价砷氧化能力以及负责该过程的微生物群落的相关研究仍较为有限。本研究设置两组实验室规模生物反应器，通过处理含三价砷废水，探究生物三价砷氧化的性能。研究结果显示，三价砷氧化可在缺氧与有氧条件下发生。动力学模型分析表明，有氧条件下的三价砷氧化速率高于缺氧条件。微宇宙实验进一步证实，生物三价砷氧化过程可由以硝酸盐或氧气作为有效电子受体的微生物驱动，表明该过程在污水处理设施中具备应用潜力。此外，本研究开展了基于DNA的稳定同位素探针（DNA-SIP）技术，以鉴定活性污泥中潜在的化能自养型三价砷氧化细菌（AOBs）。研究鉴定出与氢噬菌属（Hydrogenophaga）相关的细菌为好氧型三价砷氧化细菌，而硫杆菌属（Thiobacillus）则为依赖硝酸盐的三价砷氧化细菌。此外，通过宏基因组分箱技术，重构了多个与潜在三价砷氧化细菌相关的高质量宏基因组组装基因组（MAGs）。在这些关联三价砷氧化细菌的宏基因组组装基因组中，检测到了编码砷抗性、三价砷氧化、反硝化以及固碳的功能基因，证实其具备缺氧和/或有氧化能自养型三价砷氧化的潜力。此外，在这些宏基因组组装基因组中检测到编码次级代谢产物生物合成与胞外聚合物代谢的基因，这可能有助于潜在三价砷氧化细菌的定植，并增强其三价砷氧化能力。