Development and Characterization of a Chloroethenes-Dechlorinating Consortium Using Gluconate as a Hydrogen Donor

To evaluate the effectiveness of gluconate as a potential hydrogen donor for reductive dechlorina tion of chloroethenes, we developed a trichloroethene (TCE)-dechlorinating consortium from chloroethenes-contaminated groundwater containing Dehalococcoides using gluconate as the sole hydrogen donor and characterized its chloroethenes-dechlorinating performance and microbial com munity composition. After repeated subculturing, we successfully developed a microbial consortium with gluconate, which showed consistent dechlorination of TCE to vinyl chloride (VC), resulting in subsequent disappearance of VC. The resultant consortium could dechlorinate 24 μmol/L TCE to VC and eliminate VC within 20 days, which was similar to or slightly longer than the required time when other hydrogen donors such as lactate or methanol were used. These results indicate that gluconate can be an effective hydrogen donor for reductive dechlorination of chloroethenes. Real-time PCR and terminal restriction fragment length polymorphism analyses of bacterial and archaeal populations revealed the establishment of a stable microbial community in the developed consortium. In addition, 16S rRNA amplicon sequencing revealed that Trichococcus and Malikia were the predominant taxa, whereas Dehalococcoides and other dechlorinating populations were minor. Our results infer that the use of gluconate as a hydrogen donor established a distinctive microbial community compared with enriched consortia developed with other hydrogen donors.