Changes in the respiratory quinone profile of a soil treated with pesticides

Abstract.

The effects of the pesticides fenitrothion, chlorothalonil, chloropicrin, linuron, and simazine on the structure of microbial communities in a Nagoya University Farm soil (Typic Palehumult) were assessed for 28 days by monitoring changes in respiratory quinone profiles. Pesticides were applied to the soil at 10 times the recommended rates. Fenitrothion, linuron, and simazine did not significantly affect the total amount of quinones (an indicator of microbial biomass), the diversity of the quinones (an indicator of taxonomic diversity of the microbial community), or the composition of the quinone species (an indicator of community structure). Chlorothalonil decreased the diversity of quinones immediately after application, but no significant effect was observed after 3 days of incubation. The amount and composition of the quinones were not affected by chlorothalonil application. Application of chloropicrin decreased the amount and diversity of the quinones for 28 days. A continuous change in the structure of the microbial community in the chloropicrin-treated soil was documented by the change in the dominant quinone species. No change was observed in the control soil. It was suggested that quinone profile analysis is a potential method to detect the effect of pesticide on a soil microbial community. Less pronounced changes in the quinone profile indicated that changes in the structure of a soil microbial community may be masked by the persistent quinones from killed microorganisms.