Biodegradation of 1,2-dichloroethane by Ancylobacter sp. BL1: Degradation characteristics, catabolic genes, and bioaugmentation in contaminated soil

1,2-dichloroethane (1,2-DCA) contamination has emerged as a notable threat to human health and ecological stability. However, studies on 1,2-DCA-contaminated soils are limited. Further, the remediation potential of bacterial genera capable of the aerobic degradation of 1,2-DCA and their use in the remediation of actual 1,2-DCA-contaminated soils have not yet been comprehensively investigated. To address these research gaps, in the present study, we isolated a novel 1,2-DCA-degrading bacterial strain from 1,2-DCA contaminated soil, identified as Ancylobacter sp. BL1 using 16 S rRNA gene analysis and physiological and biochemical tests. The optimal conditions for degradation by strain BL1 were predicted using response surface methodology, and the degradation kinetics was studied. The metabolic pathway of 1,2-DCA in strain BL1 follows a hydrolytic dehalogenation mechanism. The key genes (dhlA, dhlB, max, and ald) involved in 1,2-DCA degradation exhibited significant homology with previously reported genes except for dhlB, which was located on a large plasmid together with dhlA. To the best of our knowledge, for the first time, an efficient 1,2-DCA-degrading strain, BL1, was utilized for remediating actual 1,2-DCA-contaminated soil. Our findings demonstrated that strain BL1 effectively degraded approximately 86 % of 235 mg/kg of soil 1,2-DCA within 5 days. Bioaugmentation with the isolated strain did not considerably disturb the original microbial communities of the soil, increasing the abundances of microbial flora beneficial to organic carbon degradation and restoring soil enzyme activity. Our study will provide a foundation for the bioremediation of 1,2-DCA-polluted soil.