State Key Lab of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Institute of Soil and Water Resources and Environmental Science, Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, Hangzhou 310058, China.
J Hazard Mater. 2020 Jun 5;391:122200. doi: 10.1016/j.jhazmat.2020.122200. Epub 2020 Jan 30.
Straw biochar and straw application to paddy soil dramatically altered arsenic (As) biogeochemical cycling in soil-rice system, but it remains unknown how As biotransformation microbes (ABMs) contribute to these processes. In this study, rice pot experiments combining terminal restriction fragment length polymorphism (T-RFLP) analysis and clone library were performed to characterize ABMs. Through linear discriminant analysis (LDA) effect size (LEfSe) and correlation analysis, results revealed that arrA-harbouring iron-reducing bacteria (e.g., Geobacter and Shewanella) and arsC-harbouring Gammaproteobacteria (e.g., fermentative hydrogen-producing and lignin-degrading microorganisms) potentially mediated arsenate [As(V)] reduction under biochar and straw amendments, respectively. Methanogens and sulfate-reducing bacteria (SRB) carrying arsM gene might regulate methylated As concentration in soil-rice system. Network analysis demonstrated that the association among ABMs in rhizosphere was significantly stronger than that in bulk soil. Arsenite [As(III)] methylators carrying arsM gene exhibited much stronger co-occurrence pattern with arsC-harbouring As(V) reducers than with arrA-harbouring As(V) reducers. This study would broaden our insights for the dramatic variation of As biogeochemical cycling in soil-rice system after straw biochar and straw amendments through the activities of ABMs, which could contribute to the safe rice production and high rice yield in As-contaminated fields.
秸秆生物炭和秸秆施入稻田后会显著改变土壤-水稻系统中砷的生物地球化学循环，但目前尚不清楚砷转化微生物（ABMs）如何促进这些过程。本研究通过末端限制性片段长度多态性（T-RFLP）分析和克隆文库结合的方法，对 ABMs 进行了特征描述。通过线性判别分析（LDA）效应量（LEfSe）和相关性分析，结果表明，含 arrA 的铁还原菌（如 Geobacter 和 Shewanella）和含 arsC 的γ-变形菌（如发酵产氢和木质素降解微生物）可能分别介导了生物炭和秸秆添加条件下砷酸盐（As(V)）的还原。携带 arsM 基因的产甲烷菌和硫酸盐还原菌（SRB）可能会调节土壤-水稻系统中甲基化砷的浓度。网络分析表明，根际 ABMs 之间的关联明显强于非根际土壤。携带 arsM 基因的亚砷酸盐 [As(III)] 甲基化菌与含 arsC 的 As(V)还原剂的共现模式比与含 arrA 的 As(V)还原剂的共现模式要强得多。本研究通过 ABMs 的活动，拓宽了我们对秸秆生物炭和秸秆施入后土壤-水稻系统中砷生物地球化学循环剧烈变化的认识，这有助于砷污染农田的安全水稻生产和高产。
