Exploiting the intrinsic microbial degradative potential for field-based in situ dechlorination of trichloroethene contaminated groundwater

• Published in: Journal of hazardous materials 2015-12, Vol.300, p.48-57
• Main Authors: Adetutu, Eric M., Gundry, Taylor D., Patil, Sayali S., Golneshin, Aida, Adigun, Joy, Bhaskarla, Vijay, Aleer, Samuel, Shahsavari, Esmaeil, Ross, Elizabeth, Ball, Andrew S.
• Format: Article
• Language: English
• Subjects: Bacteria - classification; Bacteria - genetics; Bacteria - metabolism; Biodegradation, Environmental; Bioremediation; Dehalococcoides; DNA, Bacterial - analysis; Geobacter; Groundwater; Groundwater - microbiology; Metagenomics; Quantitative PCR; Trichloroethene; Trichloroethylene - metabolism; Water Pollutants, Chemical - metabolism
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2015.06.055

•Cutting edge next generation sequencing tool applied to in situ TCE bioremediation.•Metagenomics showed that Epsilon- and Deltaproteobacteria were key dechlorinators.•Gammaproteobacterial groups associated with dechlorination only in untreated wells.•Accelerated TCE removal in biostimulated and bioaugmented wells compared to control.•Indigenous dechlorination potential and microbial functional redundancy observed. Bioremediation of trichloroethene (TCE) polluted groundwater is challenging, with limited next generation sequencing (NGS) derived information available on microbial community dynamics associated with dechlorination. Understanding these dynamics is important for designing and improving TCE bioremediation. In this study, biostimulation (BS), biostimulation–bioaugmentation (BS–BA) and monitored natural attenuation (MNA) approaches were applied to contaminated groundwater wells resulted in ≥95% dechlorination within 7 months. Vinyl chloride’s final concentrations in stimulated wells were between 1.84 and 1.87μgL−1, below the US EPA limit of 2.0μgL−1, compared to MNA (4.3μgL−1). Assessment of the groundwater microbial community with qPCR showed up to ∼50-fold increase in the classical dechlorinators’ (Geobacter and Dehalococcoides sp.) population post-treatment. Metagenomic assays revealed shifts from Gammaproteobacteria (pre-treatment) to Epsilonproteobacteria and Deltaproteobacteria (post-treatment) only in stimulated wells. Although stimulated wells were functionally distinct from MNA wells post-treatment, substantial dechlorination in all the wells implied some measure of redundancy. This study, one of the few NGS-based field studies on TCE bioremediation, provides greater insights into dechlorinating microbial community dynamics which should be useful for future field-based studies.