Metabolism of fluorodifen by soil microorganisms

Abstract

The metabolism of fluorodifen ( p-nitrophenyl α,α,α,-trifluoro-2-nitro- p-tolyl ether) by soil microorganisms in the presence or absence of other carbon and nitrogen sources was studied. The degradation of this herbicide continued for 5 days, when benzoate or acetate and ammonium sulphate were included in the cultures, and for more than 5 weeks when fluorodifen was used as a sole source of carbon and nitrogen. Under all conditions nitrite ions were produced at concentrations ranging between 5 and 80 per cent of the nitro-nitrogen of the fluorodifen present. The highest concentration of nitrite was obtained when added carbon sources were used with fluorodifen. The lowest nitrite concentration accumulated when the fluorodifen was used as sole source of carbon and nitrogen. The nitrite reached a maximum value after a few days of incubation, followed by rapid disappearance. p-Nitrophenol and quinol were identified in the acid-ether extract of cultures. It is suggested that the first step in the degradation of fluorodifen is the hydrolysis of the ether linkage followed by the direct elimination of the nitro-groups as nitrite ions.