Bacterial Desulfonation of the Ethanesulfonate Metabolite of the Chloroacetanilide Herbicide Metazachlor

Metazachlor (R-CH 2 -Cl), a chloroacetanilide herbicide, is converted in soil to products including the ethanesulfonate metabolite (R-CH 2 -SO 3 -; BH 479-8). Nothing is known about the degradation of the ethanesulfonates of this class of herbicides. We used inocula derived from five sources for enrichment cultures to utilize R-CH 2 -SO 3 - as a sole sulfur source for the growth of microorganisms. Each culture yielded bacteria that caused the disappearance of R-CH 2 -SO 3 - and the formation of a product identified as the glycolate metabolite (R-CH 2 -OH; BH 479-1) by mass spectrometry. A pure culture, strain HL1, was isolated, and this bacterium quantitatively desulfonated R-CH 2 -SO 3 -, the sulfur being recovered in cell protein. Recovery of the organic moiety was usually about 80%. A second ethanesulfonate (R‘-CH 2 -SO 3 - ) and two alkylsulfonates, but not taurine, were utilized by strain HL1 as sulfur sources.