MICROBIAL CYCLING OF ARSENIC AND ANTIMONY IN CONTAMINATE AND PRISTINE ENVIRONMENTS

As(V) and Sb(V) are naturally occurring toxic metals classified as pollutants of interest according by both the US EPA and World Health Organization. Their harmful effects on both ecosystem and human health have become an increasing concern for many places around the world, especially Bangladesh and Taiwan. Previous studies have demonstrated microbial reduction of As and Sb in locations with high concentrations of these metals. Less is known about microbes in environments with lower concentrations, and their potential for reduction of these metals. Microbial reduction of As(V) and Sb(V) under anoxic conditions was analyzed at two different locations at opposite ends of the toxicity spectrum. Reduction of As(V) and Sb(V) by microbes from a stibnite mine in Idaho (high concentrations of As and Sb) was compared to rates by microbes from the Binghamton University Nature Preserve (low concentrations of As and Sb). The rate of microbial reduction of As(V) and Sb(V) in the stibnite mine site was greatest under H₂ conditions. In contrast, As(V) and Sb(V) reduction was also observed in the Nature Preserve microcosms under N₂ conditions, but at a much slower rate. The ability for microbes from both locations to respire As(V) and Sb(V) suggests a common gene may exist in the microbial genome that is responsible for this ability. If more microbes are found to have the potential ability to respire As and Sb, bioremediation techniques for these toxic metals may be improved.