A number of carbamates and benzofurans which are either commercially used or generated as industrial waste are highly toxic. The N-methyl carbamates used as pesticides inhibit cholinesterase activity. They persist in some environments, causing serious health hazards. These compounds are generally biodegraded via hydrolysis or oxidation. Hydrolysis processes are relatively slow. While the oxidation mechanisms are rapid generate highly toxic metabolites, for example aldicarb (LD=0.9 mg per Kg) is oxidized to equally toxic aldicarb sulfoxide and then to aldicarb sulfone. Therefore, knowledge of the metabolic pathways involved in the detoxification of carbamates and benzofurans is important for their safe use and disposal. We have selected carbofuran (2, 3 dihydro-2.2- dimethyl-7 benzofuranyl methylcarbamate) as model compound represented both carbamates and benzofurans to investigate the biochemical pathways and genetic determinants involved in its degradation. In our previous studies several microorganisms capable of degrading carbofuran and other carbamates were isolated. These isolates utilize carbofuran as sole source of carbon or nitrogen. A Flavobacterium sp. 50085, harboring a plasmid pRC200 encodes functions for the hydrolysis of carbofuran. Another bacterium, a Pseudomonas sp. 50432 harbored several plasmids and rapidly detoxify carbofuran. One of the plasmids, pCF2 was determined to be involved in the oxidation of this compound. The proposed study is designed to investigate the mechanism of biochemical oxidation of carbofuran in strain 50432. These studies will involved the following: 1) physical mapping of the plasmid pCF2:2) purification of the enzymes responsible for the oxidation of carbofuran: and 3) generation of transposon insertion mutants. The results of this study are expected to improve our understanding of catabolism of carbofuran in Pseudomonas sp. 50432. This should then help in developing microbial agents capable of decontaminating soils/waters polluted with carbamate and benzofuran compounds as well as in devising strategies for improving the efficacy of pesticides and for their safe environmental use.
