Ngegla Janet Victoria, Zhou Xing, Chen Xiaoming, Zhu Xianbin, Liu Ziwei, Feng Jilong, Zeng Xian-Chun
State Key Laboratory of Biogeology and Environmental Geology & School of Environmental Studies, China University of Geosciences, Wuhan, PR China.
Ecotoxicology. 2020 Jan;29(1):86-96. doi: 10.1007/s10646-019-02144-9. Epub 2019 Dec 12.
Microbial arsenic (As) methylation plays important roles in the As biogeochemical cycle. However, little is known about the diversity and functions of As-methylating microorganisms from the tailings of a Realgar Mine, which is characterized as containing extremely high concentrations of As. To address this issue, we collected five samples (T1-T5) from the tailings of Shimen Realgar Mine. Microcosm assays without addition of exogenous As and carbon indicated that all the five samples possess significant As-methylating activities, producing 0.8-5.7 μg/L DMAs, and 1.1-10.7 μg/L MMAs with an exception of T3, from which MMAs was not detectable after 14.0 days of incubation. In comparison, addition of 20.0 mM lactate to the microcosms significantly enhanced the activities of these samples; the produced DMAs and MMAs are 8.0-39.7 μg/L and 5.8-38.3 μg/L, respectively. The biogenic DMAs shows significant positive correlations with the Fe concentrations and negative correlations with the total nitrogen concentrations in the environment. A total of 63 different arsM genes were identified from the five samples, which code for new or new-type ArsM proteins, suggesting that a unique diversity of As-methylating microbes are present in the environment. The microbial community structures of the samples were significantly shaped by the environmental total organic carbon, total As contents and NO contents. These data help to better understand the microorganisms-catalyzed As methylation occurred in the environment with extremely high contents of As.
微生物砷（As）甲基化在砷生物地球化学循环中起着重要作用。然而，对于雄黄矿尾矿中砷甲基化微生物的多样性和功能知之甚少，该尾矿的特点是砷含量极高。为了解决这个问题，我们从石门雄黄矿尾矿中采集了五个样本（T1 - T5）。不添加外源砷和碳的微观试验表明，所有五个样本都具有显著的砷甲基化活性，产生了0.8 - 5.7μg/L的二甲基砷（DMAs）和1.1 - 10.7μg/L的一甲基砷（MMAs），但T3除外，在培养14.0天后未检测到MMAs。相比之下，向微观体系中添加20.0 mM乳酸显著增强了这些样本的活性；产生的DMAs和MMAs分别为8.0 - 39.7μg/L和5.8 - 38.3μg/L。生物源DMAs与环境中的铁浓度呈显著正相关，与总氮浓度呈负相关。从这五个样本中总共鉴定出63个不同的arsM基因，它们编码新的或新型的ArsM蛋白，这表明环境中存在独特的砷甲基化微生物多样性。样本的微生物群落结构受到环境总有机碳、总砷含量和NO含量的显著影响。这些数据有助于更好地理解在砷含量极高的环境中微生物催化的砷甲基化过程。
