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Dichloromethane biodegradation in multi-contaminated groundwater: Insights from biomolecular and compound-specific isotope analyses.

Authors
  • Hermon, L1
  • Denonfoux, J2
  • Hellal, J3
  • Joulian, C3
  • Ferreira, S2
  • Vuilleumier, S4
  • Imfeld, G5
  • 1 Université de Strasbourg, CNRS, GMGM UMR 7156, Department of Microbiology, Genomics and the Environment, Strasbourg, France; BRGM, Geomicrobiology and Environmental Monitoring Unit, Orléans, France. , (France)
  • 2 Service Recherche, Développement et Innovation-Communautés Microbiennes, GenoScreen Lille, France. , (France)
  • 3 BRGM, Geomicrobiology and Environmental Monitoring Unit, Orléans, France. , (France)
  • 4 Université de Strasbourg, CNRS, GMGM UMR 7156, Department of Microbiology, Genomics and the Environment, Strasbourg, France. , (France)
  • 5 Université de Strasbourg, CNRS/EOST, LHyGeS UMR 7517, Laboratory of Hydrology and Geochemistry of Strasbourg, Strasbourg, France. Electronic address: [email protected] , (France)
Type
Published Article
Journal
Water research
Publication Date
Oct 01, 2018
Volume
142
Pages
217–226
Identifiers
DOI: 10.1016/j.watres.2018.05.057
PMID: 29885622
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

Dichloromethane (DCM) is a widespread and toxic industrial solvent which often co-occurs with chlorinated ethenes at polluted sites. Biodegradation of DCM occurs under both oxic and anoxic conditions in soils and aquifers. Here we investigated in situ and ex situ biodegradation of DCM in groundwater sampled from the industrial site of Themeroil (France), where DCM occurs as a major co-contaminant of chloroethenes. Carbon isotopic fractionation (εC) for DCM ranging from -46 to -22‰ were obtained under oxic or denitrifying conditions, in mineral medium or contaminated groundwater, and for laboratory cultures of Hyphomicrobium sp. strain GJ21 and two new DCM-degrading strains isolated from the contaminated groundwater. The extent of DCM biodegradation (B%) in the aquifer, as evaluated by compound-specific isotope analysis (δ13C), ranged from 1% to 85% applying DCM-specific εC derived from reference strains and those determined in this study. Laboratory groundwater microcosms under oxic conditions showed DCM biodegradation rates of up to 0.1 mM·day-1, with concomitant chloride release. Dehalogenase genes dcmA and dhlA involved in DCM biodegradation ranged from below 4 × 102 (boundary) to 1 × 107 (source zone) copies L-1 across the contamination plume. High-throughput sequencing on the 16S rrnA gene in groundwater samples showed that both contaminant level and terminal electron acceptor processes (TEAPs) influenced the distribution of genus-level taxa associated with DCM biodegradation. Taken together, our results demonstrate the potential of DCM biodegradation in multi-contaminated groundwater. This integrative approach may be applied to contaminated aquifers in the future, in order to identify microbial taxa and pathways associated with DCM biodegradation in relation to redox conditions and co-contamination levels. Copyright © 2018 Elsevier Ltd. All rights reserved.

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