Study on the microbiological degradation of bensulfuronmethyl

Abstract- Studies on the microbiological degradation of bensulfuron methyl in anaerobic conditions have made it possible to define the best operative conditions for its biodegrada-tion and the isolation and identification of metabolites. Chemical degradation, typical of all the sulfonylureas, contributes to about 30 % of the transformation of bensulfuronmethyl, whilst abiotic factors do not appear to play any role in the herbicide degradation. Biodegra-dation in anaerobiosis is particularly active in methanogenic conditions, though the ben-sulfuron methyl transformation would not seem to be due to direct action of only methanobacteria given the excessive complexity of the molecule. The extraction of the products from the culture medium led to the isolation of two pure metabolites that were characterized by 1H-NMR. The O-demethylation seems to be the first step in the degrada-tion that occurs in successive times at the expense of both the substituents of the pyrimidic ring. The investigation into the biodegradation course evidenced that the transformation of bensulfuronmethyl takes place quickly in the first 20 days and slows down until it stops completely after 40 days. Key words: sulfonylurea herbicides, microbiological degradation, degradative pathways.