The effect of toulene on the microbial community of a river in northeastern Ohio, USA

The effect of toluene on microbial communities from two sites a reference site with minimal anthropogenic disturbance and a polluted site with high levels of xenobiotic compounds along the Mahoning River (Ohio, USA) was examined in flask and microcosm experiments. Total numbers of bacteria and protozoa were determined using fluorescent stains, and bacteria of three species (Burkholderia cepacia, Pseudomonas putida and Acinetobacter calcoaceticus) were enumerated using fluorescent in situ hybridization. In water, total bacterial numbers were not adversely affected by toluene. In sediments, the number of bacteria in the toluene-treated microcosms was lower than controls, particularly in samples from the polluted site. In general, P. putida and A. calcoaceticus population sizes were lower in toluene-treated microcosms than in controls, while B. cepacia numbers were enhanced by the presence of toluene, especially in the polluted site microcosms. Treatment with toluene had a negative effect on protozoa in polluted site microcosms compared to those in reference site microcosms.