Anaerobic Arsenite Oxidation by an Autotrophic Arsenite-Oxidizing Bacterium from an Arsenic-Contaminated Paddy Soil
Anaerobic Arsenite Oxidation by an Autotrophic Arsenite-Oxidizing Bacterium from an Arsenic-Contaminated Paddy Soil
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砷污染稻田土壤中自养亚砷酸盐氧化细菌对亚砷酸盐的厌氧氧化
DOI：
10.1021/es506097c
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发表时间：
2015
影响因子：
11.4
通讯作者：
Zhao Fang-Jie
中科院分区：
文献类型：
--
作者：
Zhang Jun;Zhou Wuxian;Liu Bingbing;He Jian;Shen Qirong;Zhao Fang-Jie
微生物介导的砷氧化还原反应在砷的生态地球化学循环中起着重要作用。减少砷酸盐[As（V）]通常会导致As在水稻土中的移动和增加水稻植株对As的有效性，而亚砷酸盐[As（III）]的氧化会导致As的固定。从受砷污染的水稻土中分离到一株新的化能自养型砷氧化细菌SY。该菌株能够获得能源的氧化As（III）到As（V）在有氧和厌氧条件下使用O2或NO3-作为各自的电子受体。接种到淹水土壤中的清洗SY细胞大大增强了As（III）氧化为As（V）在溶液和吸附相的土壤。SY菌株与尼氏副球菌（Paracoccus niistensis）的16 S rRNA基因同源性为96.79%。该菌株含有反硝化和核酮糖1，5-二磷酸羧化酶/加氧酶基因簇，强调其能力，以purify和固定CO2，而耦合到As（III）氧化。缺失编码As（III）氧化酶亚基A的基因aioA，可使SY菌株对As（III）的氧化能力丧失，对As（III）的敏感性增加，表明在好氧和异养生长条件下，As（III）氧化是该菌的一种解毒机制。对aioA基因克隆文库的分析表明，土壤中绝大多数As（III）氧化细菌与α-Proteobacteria的Paracoccus属关系密切。我们的研究结果提供了直接证据的As（III）氧化的Paracoccus物种，并建议这些物种可能发挥重要作用，在水稻土中的As（III）的氧化在有氧和通风条件下。
Microbe-mediated arsenic (As) redox reactions play an important role in the biogeochemical cycling of As. Reduction of arsenate [As(V)] generally leads to As mobilization in paddy soils and increased As availability to rice plants, whereas oxidation of arsenite [As(III)] results in As immobilization. A novel chemoautotrophic As(III)-oxidizing bacterium, designated strain SY, was isolated from an As-contaminated paddy soil. The isolate was able to derive energy from the oxidation of As(III) to As(V) under both aerobic and anaerobic conditions using O2or NO3–as the respective electron acceptor. Inoculation of the washed SY cells into a flooded soil greatly enhanced As(III) oxidation to As(V) both in the solution and adsorbed phases of the soil. Strain SY is phylogenetically closely related toParacoccus niistensiswith a 16S rRNA gene similarity of 96.79%. The isolate contains both the denitrification and ribulose 1,5-bisphosphate carboxylase/oxygenase gene clusters, underscoring its ability to denitrify and to fix CO2while coupled to As(III) oxidation. Deletion of theaioAgene encoding the As(III) oxidase subunit A abolished the As(III) oxidation ability of strain SY and led to increased sensitivity to As(III), suggesting that As(III) oxidation is a detoxification mechanism in this bacterium under aerobic and heterotrophic growth conditions. Analysis of theaioAgene clone library revealed that the majority of the As(III)-oxidizing bacteria in the soil were closely related to the generaParacoccusof α-Proteobacteria. Our results provide direct evidence for As(III) oxidation byParacoccusspecies and suggest that these species may play an important role in As(III) oxidation in paddy soils under both aerobic and denitrifying conditions.