Population Change and Characteristics of Chlorothalonil-Degrading Bacteria in Soil

Microbial Degradation of the Fungicide Chlorothalonil (Part 2)

Abstract

Bacteria that degraded chlorothalonil (TPN, 2, 4, 5, 6-tetrachloro-1, 3-isophthalonitrile) were present in soils with no history of chlorothalonil application at population levels of 6×10⁶ to 12×10⁶ CFU/g-soil and were enriched by chlorothalonil application to higher population levels of 2×10⁷ to 8×10⁷ CFU/g-soil. The chlorothalonil-degrading bacteria were tolerant to high concentrations of chlorothalonil. Eleven strains of chlorothalonil-degrading bacteria were isolated and tentatively identified as Azomonas, Flavobacterium, Moraxella and Pseudomonas spp. The isolates required other carbon sources for degradation, except for those two from Flavobacterium strains that degraded chlorothalonil as a carbon and energy source. Substrate specificity was high in the two strains from Azomonas and Flavobacterium.