Bioaccumulation of mercury in marine bacteria: A novel approach of mercury remediation

Abstract

Most of the environmental bacteria that are continuously exposed to mercury present in soil and sediments of lakes and rivers might adopt the heavy metal genotype to sustain in the toxic environment. The most widely studied genetic mechanism of mercury involves mer operon mediated mechanism. mer operon present in mercury resistant bacteria harbours certain functional genes like merA, merB, merT, merP etc. merB codes for organ mercurial lyase which cleaves the C-Hg bond in organo mercurial compounds which is subsequently converted to non toxic metallic mercury by mercuric ion reductase encoded by merA gene. In the present study, for the first time an attempt has been made to understand the non mer mediated mercury resistance mechanism in potent marine bacterial isolates and their role in bioremediation of mercury contamination in the environment. Ten strains from four different sites of Odisha coast showing minimum inhibitory concentration of 25-50 ppm were isolated, which were further studied in order to deduce non mer mediated mercury resistance mechanism. The potent mercury resistant isolates when grown under mercury stress were studied to understand bioaccumulation and thus their role in mercury bioremediation in the environment. From the above results it was concluded that marine bacteria play a significant role in detoxification of mercury in the environment either by reducing it to non toxic or by accumulating it inside their cells and therefore they are a key regulator in reducing the environmental pollution.