Universality of Gluconate as a Hydrogen Donor for Reductive Dechlorination of Chloroethenes

The objective of this study was to assess the universality of gluconate as a hydrogen donor for the reductive dechlorination of chloroethenes in groundwater. For this, we conducted trichloroethene (TCE) degradation experiments using five groundwater samples collected from different chloroethenes-contaminated sites as the microbial seed and gluconate as the hydrogen donor. Although the TCE dechlorination rate was different in each groundwater, the number of genes involved in reductive dechlorination increased and chloroethenes were completely dechlorinated in all groundwater samples. In addition, the groundwater sample whose complete reductive dechlorination of TCE took a long time could also be treated by repeated gluconate supplementation, which resulted in rapid complete TCE dechlorination without the accumulation of chloroethene, a harmful metabolite. These results indicate that gluconate is a universal hydrogen donor that enables the complete reductive dechlorination of chloroethenes.