Sulfate-reducing bacteria and methanogens are involved in arsenic methylation and demethylation in paddy soils
Sulfate-reducing bacteria and methanogens are involved in arsenic methylation and demethylation in paddy soils
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DOI：
10.1038/s41396-019-0451-7
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发表时间：
2019-10-01
期刊：
影响因子：
11
通讯作者：
Zhao, Fang-Jie
中科院分区：
文献类型：
--
作者：
Chen, Chuan;Li, Lingyan;Zhao, Fang-Jie
微生物砷（As）甲基化和去甲基化是As地球化学循环的重要组成部分.淹水条件下水稻土中砷的甲基化作用增强，主要产生植物毒性物质二甲基砷（DMAs），引起水稻直穗病，这是一种在某些水稻种植区广泛发生的生理性病害。水稻土中砷甲基化和去甲基化的关键微生物类群尚不清楚。在淹水条件下培养三种水稻土。DMAs最初积累在土壤孔隙水中，随后迅速消失，同时产生甲烷。直头病稻田土壤中DMAs的产生量明显高于其他两种土壤。利用代谢抑制、功能基因转录本定量、微生物富集培养和C-13标记的DMAs，我们发现硫酸盐还原菌（SRB）和产甲烷古菌分别参与As甲基化和去甲基化，控制着水稻土中DMAs的动态。我们提出了一个水稻土砷地球化学循环的模型，连接动态变化的土壤氧化还原电位与亚砷酸盐动员，亚砷酸盐甲基化和随后的脱甲基化驱动不同的微生物类群。该模型为控制水稻直穗病的发生和DMAs的积累提供了依据。
Microbial arsenic (As) methylation and demethylation are important components of the As biogeochemical cycle. Arsenic methylation is enhanced under flooded conditions in paddy soils, producing mainly phytotoxic dimethylarsenate (DMAs) that can cause rice straighthead disease, a physiological disorder occurring widely in some rice growing regions. The key microbial groups responsible for As methylation and demethylation in paddy soils are unknown. Three paddy soils were incubated under flooded conditions. DMAs initially accumulated in the soil porewater, followed by a rapid disappearance coinciding with the production of methane. The soil from a rice straighthead disease paddy field produced a much larger amount of DMAs than the other two soils. Using metabolic inhibition, quantification of functional gene transcripts, microbial enrichment cultures and C-13-labeled DMAs, we show that sulfate-reducing bacteria (SRB) and methanogenic archaea are involved in As methylation and demethylation, respectively, controlling the dynamics of DMAs in paddy soils. We present a model of As biogeochemical cycle in paddy soils, linking the dynamics of changing soil redox potential with arsenite mobilization, arsenite methylation and subsequent demethylation driven by different microbial groups. The model provides a basis for controlling DMAs accumulation and incidence of straighthead disease in rice.