Matturro, B., L. Pierro, E. Frascadore, M.P. Papini, and S. Rossetti
Frontiers in Microbiology 9:1664

A pilot-scale plant uses poly-3-hydroxybutyrate (PHB) reactors as a slow-release source of electron donors to stimulate native organohalide-respiring bacteria (OHRB) growth to bioremediate chlorinated solvent-contaminated groundwater. Groundwater circulation wells were used to pump water into the PHB reactor before reinfiltrating the low permeability zones of the aquifer. The coupling of the biological treatment with groundwater recirculation allowed reductions in contamination level and remediation time by efficiently stimulating the growth of autochthonous OHRB and enhancing the mobilization of the pollutants. Quantitative PCR performed along the external treatment unit showed that the PHB reactor may efficiently act as an external incubator to growing Dehalococcoides mccartyi. The slow-release source of electron donors for the bioremediation process allowed the establishment of a stable population of D. mccartyi, mainly carrying bvcA and vcrA genes which are implicated in the metabolic conversion of vinyl chloride to harmless ethene. Next-generation sequencing was performed to analyze the phylogenetic diversity of the groundwater microbiome before and after the bioremediation treatment and allowed the identification of the microorganisms working closely with organohalide-respiring bacteria. https://www.frontiersin.org/articles/10.3389/fmicb.2018.01664/full