Effects of diphenylarsinic acid on bacterial and archaeal community structures in an anaerobic paddy soil

Abstract DPAA is often found as one of the major degradation products in soil and groundwater contaminated with diphenylcyanoarsine or diphenylchloroarsine. These compounds were produced mainly during the World Wars as chemical warfare agents. This study investigated the effect of DPAA contamination on soil bacterial and archaeal community structures under anaerobic conditions in a model experiment using 16S rRNA targeted PCR–DGGE fingerprinting of DNA extracted from the contaminated soil. DPAA decreased in anaerobically incubated soil cultures due to microbiological activity. Addition of rice straw partially enhanced the extent of DPAA degradation. Inorganic arsenic acid, PAA, and an unknown arsenical species were detected as degradation products using LC–ICPMS. PCR–DGGE fingerprinting for bacterial community analysis revealed that anaerobic bacterial and archaeal species, including Clostridium and Methanosarcina , became abundant in the incubated soil within a week. In the soil cultures incubated with DPAA, while a few bacterial bands found on the DGGE gels disappeared or became weaker, most of the bands showed no significant changes. Addition of DPAA had no significant effect on archaeal communities. These findings suggest that, even though DPAA may have a direct effect on some abundant bacterial species, overall bacterial and archaeal community structures under the anaerobic soil conditions tended to be stable regardless of DPAA contamination.