A Mer Operon Confers Mercury Reduction In A Staphylococcus Epidermidis Strain Isolated From Lanzhou Reach Of The Yellow River

Mercury (Hg) contaminants are widespread in Lanzhou and cause environmental pollution. Mercury pollution is harmful to environments and human health. During the past decades, mounts of evidence showed that microbes, which could be a potential alternative for mercury remediation, are able to reduce Hg (Ⅱ) to less toxic form elemental Hg by oxidation-reduction reaction. In this study, We isolated a strain named Lzu-02from sediments of the Lanzhou Reach of the Yellow River which is able to resist Hg (Ⅱ). We found that Lzu-02could significantly reduce Hg (Ⅱ) to elemental Hgaerobically when incubated in M9medium with40μM HgCl2. The optimum condition of resisting and reducing Hg (Ⅱ) for Lzu-02was pH6and37℃. Furthermore, Lzu-02was classified to be most similar to Staphylococcus epidermidis by16S sequencing analysis and Vitek phenotype identification. We also identified that Lzu-02had a mer operon consisting of SmerR, SmerC, SmerT and SmerA genes.The relative expressions of three genes (SmerC, SmerT and SmerA) were upregulated when Lzu-02was cultivated in M9medium with40μM HgCl2. Overall, our data suggested that the identified heavy metal resistant isolate Lzu-02could be useful for the bioremediation of Hg (Ⅱ) in Lanzhou reach of the Yellow River.