Unlocking the enhanced trichloroethylene bioremediation potential of mud volcano by targeting synergistic microbial stimulation and electron transfer using microbial fuel cells (MFCs)

The effectiveness of bioremediation for chlorinated organic contaminants is often constrained by the limited availability of functional degraders and electron donors, necessitating innovative strategies to enhance microbial dechlorination. This study evaluated the efficacy of mud volcano sludge (MVS) as a bioelectrochemical catalyst in microbial fuel cells (MFCs) to promote the reductive dechlorination of trichloroethylene (TCE). The treatment reactor exhibited a more rapid reduction in TCE concentrations, along with a lower redox potential (ORP) and higher electrical conductivity (EC) than the control reactor, facilitating enhanced electron transfer and TCE degradation. Full-length 16S rRNA sequencing revealed substantial shifts in the bacterial community of the treatment reactor, with an enrichment of methanotrophs, sulfate reducers, and TCE degraders, suggesting a selective stimulation of functional microbial groups involved in dechlorination. Functional gene analysis further supported these trends, revealing higher abundances of dsrA (sulfate reduction), pmoA (methanotrophy), and hydA (hydrogen metabolism) in the treatment reactor, while mcrA (methanogenesis) was more abundant in the control, indicating suppressed methanogenesis in favor of dechlorination process. Association analysis revealed that early-stage microbial communities in the treatment reactor correlated strongly with ORP and pH, favoring methanotrophs (Methylotuvimicrobium) and sulfate reducers (Desulfobulbus, Desulfurispirillum), while later-stage communities were more influenced by TDS and voltage, aligning with the enrichment of sulfate reducers (Desulfosporosinus, Desulfobacca) and bioelectrochemical activity. These findings highlight the potential of MFCs coupled with MVS to optimize microbial interactions and functional activity, paving the way for strategizing efficient and sustainable in-situ bioremediation of groundwater ecosystems contaminated with chlorinated organic compounds.