Genetic Organization and Molecular Biology

In all bacterial systems studied, resistance to mercury requires a group of about six genes. Their functions include (a) regulation so that the system will function only when needed, (b) uptake of extracellular Hg in a controlled and bound form to (c) mercuric reductase for conversion of toxic 

Hg to less toxic and volatile Hg, and sometimes (d) the additional enzyme organomercurial lyase, which cleaves the carbon-mercury bond in organomercurials such as phenylmercury and methylmercury (releasing benzene and methane plus Hg , the substrate for the mercuric reductase enzyme Walsh et al. 1988). 

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