MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, China.
Center for Applied Geosciences, University of Tübingen, Tübingen 72074, Germany.
Environ Sci Technol. 2022 Aug 16;56(16):11845-11856. doi: 10.1021/acs.est.2c01878. Epub 2022 Aug 3.
Microbial oxidation of organic compounds can promote arsenic release by reducing soil-associated arsenate to the more mobile form arsenite. While anaerobic oxidation of methane has been demonstrated to reduce arsenate, it remains elusive whether and to what extent aerobic methane oxidation (aeMO) can contribute to reductive arsenic mobilization. To fill this knowledge gap, we performed incubations of both microbial laboratory cultures and soil samples from arsenic-contaminated agricultural fields in China. Incubations with laboratory cultures showed that aeMO could couple to arsenate reduction, wherein the former bioprocess was carried out by aerobic methanotrophs and the latter by a non-methanotrophic bacterium belonging to a novel and uncultivated representative of . Metagenomic analyses combined with metabolite measurements suggested that formate served as the interspecies electron carrier linking aeMO to arsenate reduction. Such coupled bioprocesses also take place in the real world, supported by a similar stoichiometry and gene activity in the incubations with natural paddy soils, and contribute up to 76.2% of soil-arsenic mobilization into pore waters in the top layer of the soils where oxygen was present. Overall, this study reveals a previously overlooked yet significant contribution of aeMO to reductive arsenic mobilization.
微生物对有机化合物的氧化作用可以促进砷的释放，将土壤中结合的砷酸盐还原为更具移动性的亚砷酸盐形式。虽然已经证明甲烷的厌氧氧化可以还原砷酸盐，但有氧甲烷氧化（aeMO）是否以及在多大程度上可以促进还原砷的迁移仍然难以捉摸。为了填补这一知识空白，我们对来自中国砷污染农田的微生物实验室培养物和土壤样品进行了培养实验。实验室培养物的培养实验表明，aeMO 可以与砷酸盐还原偶联，其中前者的生物过程由好氧甲烷营养菌进行，后者由属于未培养的新型代表菌的非甲烷营养菌进行。宏基因组分析结合代谢物测量表明，甲酸盐作为种间电子载体，将 aeMO 与砷酸盐还原联系起来。这种偶联的生物过程也发生在现实世界中，自然稻田土壤培养实验中的类似化学计量和基因活性提供了支持，并导致土壤上层含氧孔隙水中的土壤砷迁移量高达 76.2%。总的来说，这项研究揭示了 aeMO 对还原砷迁移的一个以前被忽视但却非常重要的贡献。
