Microbial diversity of mer genes in bacteria isolated from mercury contaminated environments

Abstract

Isolated mercury resistant bacteria obtained from mercury-contaminated soils of the Carson River, NV, were analyzed for the diversity of their mercuric reductase gene, merA, by restriction fragment length polymorphisms (RFLP). It was hypothesized that the diversity would be high because the host bacteria had evolved in presence of high mercury concentrations. Following improvement of the RFLP protocol, the restriction enzymes NaeI and NciI were used in the analysis. Using NciI and NaeI, 5 and 4 distinct merA patterns were identified, respectively. None of these patterns was similar to previously described RFLP from enteric bacteria reflecting the difference between soil and gastrointestinal tract environments. Since merA loci were grouped differently by the NciI and NaeI RFLPs, loci with different DNA sequences were most likely grouped together. The improved RFLP procedure is now available for the study of merA diversity in various mercury-contaminated environments.