A benzene-degrading nitrate-reducing microbial consortium displays aerobic and anaerobic benzene degradation pathways

  • Siavash Atashgahi (Creator)
  • B.V.H. Hornung (Creator)
  • J.M. van der Waals (Creator)
  • Ulisses Nunes da Rocha (Creator)
  • F. Hugenholtz (Creator)
  • B. Nijsse (Creator)
  • Douwe Molenaar (Creator)
  • Rob Van Spanning (Creator)
  • A.J.M. Stams (Creator)
  • Jan Gerritse (Creator)
  • Hauke Smidt (Creator)



In this study, we report transcription of genes involved in aerobic and anaerobic benzene degradation pathways in a benzene-degrading denitrifying continuous culture. Transcripts associated with the family Peptococcaceae dominated all samples (21-36% relative abundance) indicating their key role in the community. We found a highly transcribed gene cluster encoding a presumed anaerobic benzene carboxylase (AbcA and AbcD) and a benzoate-coenzyme A ligase (BzlA). Predicted gene products showed >96% amino acid identity and similar gene order to the corresponding benzene degradation gene cluster described previously, providing further evidence for anaerobic benzene activation via carboxylation. For subsequent benzoyl-CoA dearomatization, bam-like genes analogous to the ones found in other strict anaerobes were transcribed, whereas gene transcripts involved in downstream benzoyl-CoA degradation were mostly analogous to the ones described in facultative anaerobes. The concurrent transcription of genes encoding enzymes involved in oxygenase-mediated aerobic benzene degradation suggested oxygen presence in the culture, possibly formed via a recently identified nitric oxide dismutase (Nod). Although we were unable to detect transcription of Nod-encoding genes, addition of nitrite and formate to the continuous culture showed indication for oxygen production. Such an oxygen production would enable aerobic microbes to thrive in oxygen-depleted and nitrate-containing subsurface environments contaminated with hydrocarbons.
Date made available1 Mar 2018
PublisherWageningen University

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