Colonization of Alcaligenes faecalis strain JBW4 in natural soils and its detoxification of endosulfan

Alcaligenes faecalis strain JBW4, a strain of bacteria that is capable of degrading endosulfan, was inoculated into sterilized and natural soils spiked with endosulfan. JBW4 degraded 75.8 and 87.0 % of α-endosulfan and 58.5 and 69.5 % of β-endosulfan in sterilized and natural soils, respectively, after 77 days. Endosulfan ether and endosulfan lactone were the major metabolites that were detected by gas chromatography–mass spectrometry. This result suggested that A . faecalis strain JBW4 degrades endosulfan using a non-oxidative pathway in soils. The ability of strain JBW4 to colonize endosulfan-contaminated soils was confirmed by polymerase chain reaction-denaturing gradient gel electrophoresis. This result suggested that strain JBW4 competed with the original inhabitants in the soil to establish a balance and successfully colonize the soils. In addition, the detoxification of endosulfan by strain JBW4 was evaluated using single-cell gel electrophoresis and by determining the soil microbial biomass carbon and enzymatic activities. The results showed that the genotoxicity and ecotoxicity of endosulfan in soil were reduced after degradation. The natural degradation of endosulfan in soil is inadequate; therefore, JBW4 shows potential for the bioremediation of industrial soils that are contaminated with endosulfan residues.