Bacterial Communities and Functional Genes Stimulated During Anaerobic Arsenite Oxidation and Nitrate Reduction in a Paddy Soil
Bacterial Communities and Functional Genes Stimulated During Anaerobic Arsenite Oxidation and Nitrate Reduction in a Paddy Soil
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水稻土厌氧亚砷酸盐氧化和硝酸盐还原过程中刺激的细菌群落和功能基因
DOI：
10.1021/acs.est.9b04308
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发表时间：
2020-02-18
影响因子：
11.4
通讯作者：
Hu, Min
中科院分区：
文献类型：
--
作者：
Li, Xiaomin;Qiao, Jiangtao;Hu, Min
微生物氧化砷（As（III））和还原硝酸盐（NO3-）可能是降低砷生物有效性和砷对水稻毒性的重要途径。然而，在未污染的土壤中，细菌群落和功能基因对As（III）在硝酸盐还原条件下的反应知之甚少。在这项研究中，厌氧水稻土微宇宙建立与As（III）和/或NO3-，探讨如何细菌群落及其功能基因的刺激过程中As（III）的氧化和硝酸盐还原。硝酸盐的加入大大加速了As（III）到As（V）的微生物氧化，而硝酸盐的还原不受As（III）的加入。宏基因组分析表明，硝酸盐还原菌主要属于Pseudogulbenkiania，具有narG、nirS和norBC基因。假定的As（III）氧化细菌由Azoarcus sp.占主导地位，在其基因组草图中检测到As（III）氧化酶基因aioA和aioB，其也具有完整的反硝化基因（主要是napA，nirK和nosZ）。定量PCR分析证实，aioA和nosZ基因通过As（III）的添加而增强。这些发现表明了固氮线虫和拟古氏线虫相关物种的重要性，这两种土壤在As（III）氧化与硝态氮还原耦合过程中表现出不同的砷、氮土壤化学生理生态特征。
Microbial arsenite (As(III)) oxidation associated with nitrate (NO3-) reduction might be an important process in diminishing arsenic bioavailability and toxicity to rice when paddy soils are contaminated by arsenic. In a noncontaminated soil, however, the responses of bacterial communities and functional genes to As(III) under nitrate-reducing conditions are poorly understood. In this study, anaerobic paddy soil microcosms were established with As(III) and/or NO3- to investigate how the bacterial communities and their functional genes were stimulated during As(III) oxidation and nitrate reduction. Microbial oxidation of As(III) to As(V) was substantially accelerated by nitrate addition, while nitrate reduction was not affected by As(III) addition. Metagenomic analysis revealed that nitrate-reducing bacteria were principally affiliated with Pseudogulbenkiania, with narG, nirS, and norBC genes. Putative As(III)-oxidizing bacteria were dominated by an Azoarcus sp. with As(III) oxidase genes aioA and aioB detected in its draft genome, which also had complete sets of denitrification genes (mainly, napA, nirK, and nosZ). Quantitive PCR analysis confirmed that the abundance of Azoarcus spp., aioA, and nosZ genes was enhanced by As(III) addition. These findings suggest the importance of Azoarcus-and Pseudogulbenkiania-related spp., both of which showed various physio-ecological characteristics for arsenic and nitrogen biogeochemistry, in coupling As(III) oxidation and nitrate reduction in flooded paddy soil.