Chlorinated ethene biodegradation and associated bacterial taxa in multi-polluted groundwater: Insights from biomolecular markers and stable isotope analysis

Chlorinated ethenes (CEs) are most problematic pollutants in groundwater. Dehalogenating bacteria, and particular organohalide-respiring bacteria (OHRB), can transform PCE to ethene under anaerobic conditions, thus contribute bioremediation of contaminated sites. Current approaches characterize situ biodegradation CEs include hydrochemical analyses, quantification the abundance key species (e.g. Dehalococcoides mccartyi) dehalogenase genes (pceA, vcrA, bvcA tceA) involved different steps organohalide respiration (OHR) by qPCR, compound-specific isotope analysis (CSIA) CEs. Here we combined these with sequencing 16S rRNA gene amplicons consider both OHRB bacterial taxa CE transformation at a multi-contaminated site. Integrated hydrogeochemical characteristics, abundances diversity shows that mainly correlated suggesting pollutant exposure acts as central driver diversity. CSIA, four reductive encoding prevalence highlighted sustained PCE, DCE VC degradation several wells polluted plume. These results suggest associated OHR play an essential role natural attenuation CEs, representatives including Dehalobacterium Desulfosporosinus co-occur Dehalococcoides. Overall, our study emphasizes benefits combining evaluate interplay between dynamics CE-polluted plumes more robust assessment multi-polluted