Ubiquitous capability to substitute chlorine atoms of chlorothalonil in bacteria

Abstract

Thirty-seven strains of bacteria belonging to various taxonomic positions were examined for the degrading ability of a fungicide chlorothalonil, 2, 4, 5, 6-tetrachloroisophthalonitrile, in nutrient broth. All of the bacteria degraded chlorothalonil, except Pimelobacter sp. A3. On the chlorothalonil-suspended agar, most of the Gram-negative bacteria grew but many Gram-positive bacteria did not grow. No production of 14CO2 was observed in the degradation of [1-nitrile-14C]-chlorothalonil. The degradation of chlorothalonil was mainly observed in the exponential growth stage of bacteria. Methylthiotrichloroisophthalonitrile and hydroxytrichloroisophthalonitrile were major metabolites. Trichloroisophthalonitrile was detected as a minor metabolite. These findings suggested that the capability to degrade chlorothalonil by the substitution reaction of chlorine atoms on aromatic ring with methylthio group, hydroxyl group or hydrogen is ubiquitous in bacteria.