Rapid degradation of carbaryl by two novel strains ofArthrobacter spp. isolated from forest soil

Carbaryl is one of the carbamate insecticides widely used in agricultural fields and forests. To restore the environment contaminated with carbaryl application, it is suggested that microbial degradation of carbaryl could be an effective method. Two novel bacterial strains degrading rapidly carbaryl were isolated from forest soil. These strains designated as 19B and 19C were identified as novel species ofArthrobacter, respectively based on main bacterial properties including GC-content, major fatty acid composition, major menaquinone isoprenologue and 16S rRNA gene sequence analysis. Strain 19B started to degrade carbaryl within several hours and completely degraded 50μg/ml carbaryl in a mineral salt medium within a day. Similarly, strain 19C showed a high degradation ability. Gas chromatography-mass spectrometry analysis showed that the major degradation metabolite is 1-naphthol (M=144) and minor metabolites are 1,4-naphthalenedione (M=158) and 1,4-naphthalenediol (M=160), suggesting a pathway of carbaryl degradation by both strains. This research was supported by a Grant-in-Aid from the Ministry of Agriculture, Forestry and Fisheries, Japan.