Shewanella oneidensis MR-1对不同价态砷的生物转化与甲基化

在实验室纯培养条件下,通过分别向培养基中投加As(Ⅲ)和As(Ⅴ),探讨Shewanella oneidensis MR-1对不同价态砷的生物转化与甲基化作用.结果表明,S.oneidensis MR-1介导下不同价态砷的生物转化与微生物对砷的耐受和代谢特性有着密切联系,在投加As(Ⅲ)时,由于细胞自身的解毒作用会产生少量的As(Ⅴ),同时在酶的作用下As(Ⅲ)与甲基供体结合生成甲基砷;而在投加As(Ⅴ)时,遵循Challenge机制,先产生一甲基砷后生成二甲基砷.此外,弱酸性环境比碱性更有利于甲基砷的产生;温度30℃时甲基砷的产生量较高,过低或过高的培养温度砷甲基化率下降.

Biotransformation and methylation of different valence state arsenic by Shewanella oneidensis MR-1

The biotransformation and methylation of arsenic by Shewanella oneidensis MR-1 were studied under laboratory condition with the addition of As (III) and As (V) respectively to the culture medium. The result showed the biotransformation of arsenic by S. oneidensis MR-1 was dependent on microbe tolerance and metabolism. When As (III) was added to the medium, a small quantity of As (V) was generated by S. oneidensis MR-1for detoxification, meanwhile organic arsenic was generated by the action of methyltransferase. When As (V) was added to the medium, monomethylarsine and dimethylarsine were produced step by step through the Challenge mechanism. In addition, weakly acidic environment was more beneficial to arsenic methylation than alkaline condition. When the culture temperature was 30℃, the arsenic methylation rate was higher than others.