The efficiencies of inorganic mercury bio-methylation by aerobic bacteria under different oxygen concentrations

文献类型： 外文期刊

第一作者： Cao, Dan

作者： Cao, Dan;Chen, Weihong;Xiang, Yuping;Liu, Hang;Feng, PengYu;Shen, Hong;Zhang, Cheng;Wang, Yongmin;Wang, Dingyong;Mi, Qianfen;Shen, Hong;Zhang, Cheng;Wang, Yongmin;Wang, Dingyong;Shen, Hong;Zhang, Cheng;Wang, Yongmin;Wang, Dingyong

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关键词： gamma-Proteobacteria; Pseudomonas fluorescens TGR-B2; Pseudomonas putida TGR-B4; Mercury bio-methylation; Aerobic and/or facultative anaerobic bacteria; Oxygen concentration

期刊名称：ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY （ 影响因子：6.2； 五年影响因子：6.3 ）

ISSN： 0147-6513

年卷期： 2021 年 207 卷

页码：

收录情况： SCI

摘要： Limited information is available about the bio-methylation of inorganic mercury (iHg) under aerobic conditions. In this study, two gamma-proteobacteria strains (P. fluorescens TGR-B2 and P. putida TGR-B4) were obtained from the soil of The Three Gorges Reservoir (TGR), demonstrating effective aerobic transformation capacities of iHg into methylmercury (MeHg). Based on periodical changes in soil oxygen content of the TGR, a culture system was established, in which 300 ng Hg (II) L-1 and O-2 were set at 7%, 14%, and 21%, respectively. Results indicated that the two strains differed significantly in bacterial growth rate and MeHg production. The kinetic model of MeHg showed typical characteristics of a "two-staged" process: The first stage was dominated by biomethylation, which was shown by increasing of net MeHg content. Moreover, the second stage was dominated by bio-demethylation, which decreased net MeHg content. Thus, we hypothesized that the mechanism of aerobic bacterial iHg bio-methylation: (1) should inefficiency compared to anaerobic bacteria i.e.SRB, which were regulated by hgcA/B gene clusters, (2) might be regarded as a passive stress response and depended on the bacterial iHg intoxication threshold and MeHg tolerance threshold.

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