Biodegradation of carbendazim by a potent novelChryseobacteriumsp. JAS14 and plant growth promotingAeromonas caviaeJAS15 with subsequent toxicity analysis

In the present study, carbendazim (MBC) degrading bacterial strains were isolated and identified asChryseobacteriumsp. JAS14 andAeromonas caviaeJAS15. Both the strains completely degraded 200 mg l(-1)of MBC in the aqueous medium and soil within 4-9 days of incubation. In an aqueous medium, the degradation process was characterized by a rate constant of 53.16 day(-1)and 42.60 day(-1), following zero order model and DT(50)was 1.8 days and 2.34 days forChryseobacteriumsp. JAS14 andA. caviaeJAS15, respectively. AChryseobacteriumsp. JAS14 andA. caviaeJAS15 inoculated into the soil without the addition of nutrients showed the degradation rate constant of 27.30 day(-1)and 23.87 day(-1), and DT(50)was 3.66 days and 4.18 days, respectively. The metabolites during MBC biodegradation byChryseobacteriumsp. JAS14 andA. caviaeJAS15 were identified as 2-aminobenzimidazole, 2-hydroxybenzimidazole, 1, 2 diaminobenzene and catechol. To our knowledge, this is the first study of the detailed biodegradation pathway of MBC byChryseobacteriumsp. JAS14 was proposed. Phytotoxicity and cytogenotoxicity assays showed that the toxicity of the MBC reduced after biodegradation byChryseobacteriumsp. JAS14 andA. caviaeJAS15. In addition,A. caviaeJAS15 possess important plant growth promoting traits under normal and MBC stress condition. These results suggest theChryseobacteriumsp. JAS14 andA. caviaeJAS15 could be used as a bioresource for the reclamation of MBC contaminated soil.