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

Sci Rep. 2018 Mar 14;8(1):4490. doi: 10.1038/s41598-018-22617-x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anaerobiosis*
  • Benzene / metabolism*
  • Biodegradation, Environmental
  • Biofilms
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial
  • Metabolic Networks and Pathways*
  • Microbial Consortia*
  • Nitrates / metabolism*
  • Oxidation-Reduction
  • Oxygen / metabolism
  • Peptococcaceae / genetics
  • Peptococcaceae / growth & development
  • Peptococcaceae / metabolism*
  • Transcriptome


  • Nitrates
  • Benzene
  • Oxygen