Chlorinated ethenes (CEs) are the second most common contaminant worldwide. Remediation procedures combining treatment with nanoscale zero-valent iron (nZVI) and anaerobic microbial degradation supported by electric current belongs to one of the most successful approaches. Here we describe an effect of electric current on indigenous microbial degraders of CE during a field study. Groundwater samples were taken from anode well, four cathode wells and three control wells and isolated DNA was analysedanalyzed using real-time PCR. Total bacterial biomass was quantified using 16S rDNA gene. Markers of organohalide respiration included Dehalococcoides sp., Desulfitobacterium spp. and vinyl chloride (VC) reductases vcrA and bvcA. Denitrifying bacteria were determined by nirK marker and sulfate reducing bacteria by apsA2. Representative samples were analysedanalyzed using NGS method targeted to the V4 region of 16S rDNA gene. qPCR analysis of the anode well reveal significant decrease in all tested markers connected to eminent decrease in pH to strongly acidic values. Cathode wells maintained high level of bacterial growth even if there were slight changes in pH. Composition of bacterial communities in the anode and cathode wells strongly differed and changed over time. In the control wells, a long-term stability in composition of bacterial community was observed. To conclude, electric current caused decrease in organohalide bacteria and other markers in the anode well, all other wells showed ongoing organohalide respiration important for CEs degradation.Keywords: electric current, NGS, nZVI, organohalide respiration, qPCR.
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