Isolation and characterization of a carbendazim-degrading Rhodococcus sp. djl-6

Bacterium djl-6, capable of degrading carbendazim, was isolated by continuous enrichment culture originating from carbendazim-treated soil. The isolate was identified as Rhodococcus sp. according to its phenotypic features, physiologic and biochemical characteristics, and phylogenetic analysis. The strain could use carbendazim as sole carbon or nitrogen source. It showed a high average degradation rate of 55.56 mg . L(-1) . d(-1) in M9 medium amended with carbendazim. High-pressure liquid chromatography-mass spectrometry (HPLC-MS) analysis showed the presence of 2-aminobenzimidazole, benzimidazole, and an unknown metabolite with molecular ions (M(+)) of m/z 104.8 and 118.5. The degradation in the isolate djl-6 seems to be initiated with the cleavage of the methyl carbemate side chain, resulting in the formation of 2-aminobenzimidazole and benzimidazole. This is the first report of the intermediates benzimidazole and 2-aminobenzimidazole found together in the culture filtrate of pure bacterium.