Isolation and characterization of mercury-resistant bacteria associated with merA gene

Mercury-resistant bacteria are able to detoxify mercury by reducing highly toxic mercury ions (Hg') to relatively less toxic, volatile elemental mercury (Hg") and subsequent diffusional loss of Hg" from bacterial cells. This reaction is mediated by mercury reductase enzyme, an inducible intracellular enzyme encoded by merA gene in the mer operon. In this study, six mercury-resistant bacteria were successfully isolated from contaminated soil and oil sludge. The samples containing mercury-resistant bacteria were enriched in Nutrient Broth (NB) containing 25ppm HgCb_ Subsequently, six mercury-resistant bacteria were selected and sub-cultured on Luria Bertani (LB) agar containing 25ppm HgCli to obtain pure cultures. Among the six bacterial isolates, three of them were selected for further analysis by amplifying their mer A gene using Polymerase Chain Reaction (PCR) with sequence specific PCR primers, namely merAl and merA5. PCR fragments with molecular size of approximately 900bp were successfully amplified from two of the selected bacterial isolates, possibly to be from genus Klebsiella and Streptococcus