Alternative biodegradation pathway of the herbicide diuron

Abstract

Native soil microbiota is important to maintain the quality of the environment, but with the intensive use of agrochemicals, changes in microbial biomass and formation of toxic waste have been observed. Studies have emphasized the importance of using bioremediation to reduce the diuron in the environment, as well as other pesticides. The biodegradation of diuron is usually described under aerobic conditions, in which microorganisms perform an N-demethylation of the urea group and subsequent hydrolysis, producing three different metabolites: 3-(3,4-dichlorophenyl)-3-methylurea, 3,4-dichlorophenylurea, and 3,4-dichloroaniline. In this study, the biodegradation of this herbicide by bacteria isolated from a sugarcane cultivation area and the degradation pathway of diuron were evaluated. The metabolites generated from diuron biodegradation were analyzed by High Performance Liquid Chromatography coupled to a mass spectrometer with an electrospray ionization source and ion trap analyzer. Isolate S204, identified as Escherichia fergusonii by sequencing of the 16S rDNA, adk, gyrB and recA was able to remove the chlorine from the herbicide molecule, as well as forming the metabolites already described. Therefore, these results suggest that isolate S204 can degrade diuron by a different pathway not yet described.