Occurrence of bacterial resistance to arsenite, copper, and selenite in adverse habitats

Abstract

The effects of metal pollution on biotic communities has been extensively studied, particularly in the areas of ecotoxicology and species composition effects. Impact studies on bacterial communities have focused on adaptation via resistance mechanisms or biogeochemical cycling alterations. It has been shown that microbial communities in polluted environments are frequently resistant to higher levels of organics and metals than those in unimpacted areas. Increases in bacterial resistance to metals and metalloids has been attributed to selection and molecular mechanisms, such as gene transfer via plasmids. Relatively few natural environments have been surveyed for metal resistant bacterial populations, with most studies measuring mercury, lead or zinc resistance. Thus, the incidence of naturally-occurring and pollutant-related microbial resistance is poorly defined, as are the environmental factors which influence resistance. Elevated levels of arsenic, copper, and selenium have caused environmental impacts which are linked to agricultural, industrial, and municipal activities. The present study reports the incidence of aerobic heterotrophic bacterial resistance to arsenite, selenite and copper in a variety of habitats in the United States. These included soil, water, and sediments with know copper, arsenic, or selenium pollution, as well as control sites.