Population Change and Characteristics of Chlorothalonil-Degrading Bacteria in Soil*

Abstract

Bacteria that degraded chlorothalonil (TPN, 2,4,5,6-tetrachloro-l,3-isophthalonitrile) were present in soils with no history of chlorothalonil application at population levels of 6 X 106 to 12 X 106 CFU/g-soil and were enriched by chlorothalonil application to higher population levels of 2xl07 to 8 x 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. © 1991, Pesticide Science Society of Japan. All rights reserved.