Key Laboratory of Water Quality and Conservation in the Pearl River Delta, Ministry of Education, School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China.
National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Institute of Eco-environmental and Soil Sciences, Guangdong Academy of Sciences, Guangzhou 510650, China.
Environ Pollut. 2022 Nov 1;312:120040. doi: 10.1016/j.envpol.2022.120040. Epub 2022 Aug 28.
Arsenite (As(III)) is more toxic, mobilizable and bioavailable than arsenate (As(V)). Hence, the transformations between As(III) and As(V) are crucial for the toxicity and mobility of arsenic (As). However, As transformation and microbial communities involved in alkaline soils are largely unknown. Here we investigate two major pathways of As transformation, i.e., As(III) oxidation and As(V) reduction, and identify the bacteria involved in the alkaline soil by combining stable isotope probing with shotgun metagenomic sequencing. As(III) oxidation and significant increase of the aioA genes copies were observed in the treatments amended with As(III) and NO, suggesting that As(III) oxidation can couple with nitrate reduction and was mainly catalyzed by the microorganisms containing aioA genes. As(V) reduction was detected in the treatments amended with As(V) and acetate where the abundance of arrA gene significantly increased, indicating that microorganisms with arrA genes were the key As(V) reducers. Acidovorax, Hydrogenophaga, and Ramlibacter were the putative nitrate-dependent As(III) oxidizers, and Deinococcus and Serratia were the putative respiratory As(V) reducers. These findings will improve our understanding of As metabolism and are meaningful for mapping out bioremediation strategies of As contamination in alkaline environment.
砷酸盐（As(V)）比亚砷酸盐（As(III)）毒性更大、迁移性更强、生物可利用性更高。因此，As(III)和 As(V)之间的转化对于砷的毒性和迁移性至关重要。然而，碱性土壤中砷的转化和微生物群落仍知之甚少。本研究通过结合稳定同位素示踪法和鸟枪法宏基因组测序，调查了两种主要的砷转化途径，即 As(III)氧化和 As(V)还原，并确定了参与碱性土壤中砷转化的细菌。在添加 As(III)和硝酸盐的处理中观察到 As(III)氧化和 aioA 基因拷贝数的显著增加，表明 As(III)氧化可以与硝酸盐还原偶联，主要由含有 aioA 基因的微生物催化。在添加 As(V)和乙酸盐的处理中检测到 As(V)还原，arrA 基因的丰度显著增加，表明具有 arrA 基因的微生物是关键的 As(V)还原菌。 Acidovorax、 Hydrogenophaga 和 Ramlibacter 可能是依赖硝酸盐的 As(III)氧化菌，而 Deinococcus 和 Serratia 可能是呼吸型的 As(V)还原菌。这些发现将提高我们对砷代谢的认识，对制定碱性环境中砷污染的生物修复策略具有重要意义。
