Efficient Arsenic Methylation and Volatilization Mediated by a Novel Bacterium from an Arsenic-Contaminated Paddy Soil.
Efficient Arsenic Methylation and Volatilization Mediated by a Novel Bacterium from an Arsenic-Contaminated Paddy Soil.
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砷污染水稻土中新型细菌介导的高效砷甲基化和挥发
DOI：
10.1021/acs.est.6b01974
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发表时间：
2016-06-21
影响因子：
11.4
通讯作者：
Zhao FJ
中科院分区：
文献类型：
--
作者：
Huang K;Chen C;Zhang J;Tang Z;Shen Q;Rosen BP;Zhao FJ
微生物砷的甲基化和挥发是控制水稻土砷地球化学循环的重要过程。为了进一步了解这些过程，我们从砷污染的水稻土中分离到一株新的细菌SM-1。SM-1具有较强的砷甲基化和挥发能力，在24 h内，几乎所有的亚砷酸盐（10 µM）转化为二甲基胂酸盐和三甲基氧化砷，三甲基胂气体进入顶空，三甲基胂占总砷的近一半。根据16 S rRNA序列，菌株SM-1代表噬细胞科中的一个新属中的一个新种。菌株SM-1在水稻土中含量丰富，接种SM-1后，土壤中As的甲基化和挥发都有明显的增强。从SM-1中克隆了亚砷酸甲基转移酶基因（ArarsM）。在大肠杆菌中表达后，ArArsM赋予了大肠杆菌As甲基化和挥发能力。提高了其对亚砷酸盐的抗性。SM-1的高As甲基化和挥发能力可能归因于有效的ArArsM酶加上低亚砷酸盐流出。这些结果表明，SM-1菌株在水稻土砷的甲基化和挥发过程中起着重要作用，具有很大的砷生物修复潜力。
Microbial arsenic (As) methylation and volatilization are important processes controlling the As biogeochemical cycle in paddy soils. To further understand these processes, we isolated a novel bacterial strain, SM-1, from an As-contaminated paddy soil. SM-1 showed strong As methylation and volatilization abilities, converting almost all arsenite (10 µM) to dimethylarsenate and trimethylarsenic oxide in the medium and trimethylarsine gas into the headspace within 24 h, with trimethylarsine accounting for nearly half of the total As. On the basis of the 16S rRNA sequence, strain SM-1 represents a new species in a new genus within the family Cytophagaceae. Strain SM-1 is abundant in the paddy soil and inoculation of SM-1 greatly enhanced As methylation and volatilization in the soil. An arsenite methyltransferase gene (ArarsM) was cloned from SM-1. When expressed in Escherichia coli, ArArsM conferred the As methylation and volatilization abilities to E. coli and increased its resistance to arsenite. The high As methylation and volatilization abilities of SM-1 are likely attributed to an efficient ArArsM enzyme coupled with low arsenite efflux. These results suggest that strain SM-1 plays an important role in As methylation and volatilization in the paddy soil and has a great potential for As bioremediation.