Acclimation of Aquatic Microbial Communities to Hg(II) and CH3Hg(+) in PollutedFreshwater Ponds

摘要

The relationship of mercury resistance to the concentration and chemicalspeciation of mercurial compounds was evaluated for microbial communities of mercury-polluted and control waters. Methodologies based on the direct viable counting (DVC) method were developed to enumerate mercury-resistant communities. Elevated tolerance to Hg(II) was observed for the microbial community of one mercury polluted pond as compared to the community of control waters. These results suggest an in situ acclimation to Hg(II). The results of the methylmercury resistance-DVC assay suggested that minimal acclimation to CH3Hg(+) occurred since similar concentrations of CH3HgCl inhibited growth of 50% of organisms in both the control and polluted communities. Analyses of different mercury species in pond waters suggested that total mercury, but not CH3Hg(+) concentrations, approached toxic levels in the polluted ponds. Thus, microbial acclimation was specific to the chemical species of mercury that were present in the water at high enough concentration to cause toxic effects. (Copyright (c) Springer-Verlag New York Inc. 1991.)