Topic Area: 2f. Challenges in Application of Bioremediation Tools

Formatted Title:

It’s More Than Just Dehalococcoides, Reductive Dechlorination Takes a Village

Background/Objectives:

There are multiple strains of Dehalococcoides mccartyi (Dhc) with different capabilities that are important during the bioremediation of chlorinated ethenes. Some Dhc can tolerate more oxidizing conditions, some Dhc can fix their own nitrogen, some Dhc may be more tolerant of low pH, and some Dhc are complete dechlorinators of PCE and TCE to ethene. In addition to their intrinsic capabilities, Dhc rely on other microbes including Geobacter to dechlorinate high concentrations of PCE and TCE in DNAPL zones, Dehalobacter, that are dechlorinators of tri-halogenated compounds, which are inhibitory to Dhc, and Acetobacterium, a vitamin B12 producer that synthesizes this essential Dhc nutrient. This study highlights how the types of Dhc vary across bioaugmented and non-bioaugmented sites and provides evidence of how synergistic microbes collaborate with Dhc populations leading to successful remediation outcomes. The insights provided by measuring these key microbial populations helps identify site challenges and optimize bioremediation performance.

Approach/Activities:

Molecular biological tools including quantitative PCR and next generation sequencing were used to assess Dhc, and associated microbial populations, at a variety of bioaugmented chlorinated solvent remediation sites including those with DNAPL, mixed contaminants, low pH, and sites with less extreme conditions. The dynamics of various Dhc strains were examined by quantifying Dhc reductive dehalogenase (Rdase) genes (pceA, tceA, bvcA and vcrA) as well as nifD, which fixes nitrogen. Other microbial partners including Geobacter, Dehalobacter and Acetobacterium were also examined.

Jennifer Wilkinson

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(Group 2, Poster Board #50) It’s More Than Just Dehalococcoides, Reductive Dechlorination Takes a Village