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Effect of Antibiotics on Redox Transformations of Arsenic and Diversity of Arsenite-Oxidizing Bacteria in Sediment Microbial Communities

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journal contribution
posted on 2014-01-07, 00:00 authored by Shigeki Yamamura, Keiji Watanabe, Wataru Suda, Shun Tsuboi, Mirai Watanabe
In the present study, we investigated the effect of antibiotics on microbial arsenate (As­(V)) reduction and arsenite (As­(III)) oxidation in sediments collected from a small pond and eutrophic lake. The As­(V)-reducing activities were less susceptible to chloramphenicol in aerobic conditions than in anaerobic conditions. Aerobic As­(V) reduction proceeded in the presence of diverse types of antibiotics, suggesting that As-resistant bacteria are widely antibiotic resistant. In contrast, some antibiotics, e.g., chloramphenicol, strongly inhibited aerobic As­(III) oxidation. In addition, bacterial As­(III) oxidase genes were scarcely amplified and Proteobacteria-related 16S rRNA genes drastically decreased in chloramphenicol-amended cultures. Erythromycin and lincomycin, which successfully target many Gram-positive bacteria, scarcely affected As­(III) oxidation, although they decreased the diversity of As­(III) oxidase genes. These results indicate that the aerobic As­(III) oxidizers in the sediment cultures are mainly composed of Proteobacteria and are more sensitive to certain types of antibiotics than the aerobic As­(V) reducers. Our results suggest that antibiotic disturbance of environmental microbial communities may affect the biogeochemical cycle of As.