Chlorothalonil degradation under anaerobic conditions in an agricultural tropical soil

Chlorothalonil, a halogenated benzonitrile compound, is one of the most widely used fungicides in the world. Anaerobic microcosm assays were established to evaluate the combined effect of the initial content of carbon (6.3, 9.45 and 12.6 mg g(-1)), nitrogen (0.6, 1.8 and 3 mg g(-1)) and chlorothalonil (432, 865 and 1298 etag g(-1)) on the biodegradation of this fungicide by microbiota from an agricultural tropical soil. A Box-Behnken experimental design was used and chlorothalonil depletion was followed by HPLC with UV detection. The initial carbon content and fungicide dose were found to have a significant effect on removal efficiency. After 25 days of incubation, a high chlorothalonil depletion was observed in all biologically active microcosms (56 - 95%) although abiotic loss in a sterile blank was also notable (37%). The results suggest a high potential for chlorothalonil biodegradation under anaerobic conditions by indigenous microbial communities from soil that has been continuously exposed to high doses of the fungicide.