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Diverse dechlorinators and dechlorination genes enriched through amendment of chlorinated natural organic matter fractions

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Abstract

In uncontaminated environments, chlorinated natural organic matter (Cl-NOM) can act as an electron acceptor for organohalide-respiring bacteria. It is unknown, however, whether different types of Cl-NOM are preferentially dechlorinated or whether enrichment with Cl-NOM affects the ability of bacteria to dechlorinate contaminants. In this research NOM was extracted from sediment, fractionated based on hydrophobicity, and either amended to polychlorinated biphenyl-contaminated soil directly or chlorinated and then amended to soil. Amendments of the least hydrophobic Cl-NOM fraction were dechlorinated most rapidly, followed by the moderately hydrophobic Cl-NOM fraction. Soil that had been enriched on the moderately hydrophobic fraction of Cl-NOM was also capable of faster dechlorination of the contaminants trichloroethene and tetrachlorobenzene. Community analysis of the soil during enrichment showed that some known organohalide-respiring bacteria were present and may have played a role in dechlorination; nevertheless, many bacteria appeared to be enriched during both Cl-NOM and contaminant dechlorination. In addition, the quantities of two haloalkane dehalogenase genes increased during enrichment on Cl-NOM. These results show for the first time that Cl-NOM can prime contaminant dechlorination and also suggest that hydrolytic dechlorination processes were involved in both Cl-NOM and contaminant dechlorination.

Graphical abstract: Diverse dechlorinators and dechlorination genes enriched through amendment of chlorinated natural organic matter fractions

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Supplementary files

Article information


Submitted
30 Oct 2019
Accepted
23 Dec 2019
First published
31 Dec 2019

Environ. Sci.: Processes Impacts, 2020, Advance Article
Article type
Paper

Diverse dechlorinators and dechlorination genes enriched through amendment of chlorinated natural organic matter fractions

H. R. Temme and P. J. Novak, Environ. Sci.: Processes Impacts, 2020, Advance Article , DOI: 10.1039/C9EM00499H

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