Enrichment of a microbial consortium for 1,1,2-trichloroethane remediation: Insights into dechlorinators and...

Chlorinated aliphatic hydrocarbons (CAHs), such as 1,1,2-trichloroethane (1,1,2-TCA), are persistent groundwater pollutants with high toxicity and carcinogenicity. Anaerobic reductive dechlorination by organohalide-respiring bacteria (OHRB) offers a promising remediation strategy. In this study, a stable microbial consortium, designated ZJGTCA, was enriched and shown to dechlorinate 1,1,2-TCA to ethene, achieving a complete dechlorination rate of 51.22 μM·day⁻¹ and a dihaloelimination rate of 2150 μM·day⁻¹ . Microbial succession analyses identified Trichlorobacter and Dehalococcoides as key dechlorinators, with qPCR quantifying their abundances as 2.82 × 10 ¹⁰ and 8.92 × 10 ¹¹ copies·L⁻¹ , respectively. Network and metagenomic analyses revealed that Trichlorobacter and Citrobacter contribute critically to cofactor biosynthesis, including biotin, thiamine, and cobalamin pathways. Metagenome-assembled genome (MAG) analysis further established a microbial interaction model in which Trichlorobacter performs dihaloelimination, Dehalococcoides completes hydrogenolysis, and both Trichlorobacter and Citrobacter act as cofactor producers. Fermentative bacteria such as Sphaerochaeta metabolize lactate, propionate, and long-chain fatty acids into acetate and H₂, supporting dechlorinators. These complementary functions highlight the ecological interactions sustaining efficient 1,1,2-TCA reductive dechlorination. The ZJGTCA consortium represents a promising bioaugmentation agent for CAHs-contaminated groundwater, offering insights into enhancing pollutant degradation and maintaining microbial community stability.