DNA-SIP identifies sulfate-reducing Clostridia as important toluene degraders in tar-oil-contaminated aquifer sediment

Christian Winderl, Holger Penning, Frederick Von Netzer, Rainer U. Meckenstock, Tillmann Lueders

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90 Scopus citations


Global groundwater resources are constantly challenged by a multitude of contaminants such as aromatic hydrocarbons. Especially in anaerobic habitats, a large diversity of unrecognized microbial populations may be responsible for their degradation. Still, our present understanding of the respective microbiota and their ecophysiology is almost exclusively based on a small number of cultured organisms, mostly within the Proteobacteria. Here, by DNA-based stable isotope probing (SIP), we directly identified the most active sulfate-reducing toluene degraders in a diverse sedimentary microbial community originating from a tar-oil-contaminated aquifer at a former coal gasification plant. On incubation of fresh sediments with 13C7-toluene, the production of both sulfide and 13CO2 was clearly coupled to the 13C-labeling of DNA of microbes related to Desulfosporosinus spp. within the Peptococcaceae (Clostridia). The screening of labeled DNA fractions also suggested a novel benzylsuccinate synthase alpha-subunit (bssA) sequence type previously only detected in the environment to be tentatively affiliated with these degraders. However, carbon flow from the contaminant into degrader DNA was only ∼50%, pointing toward high ratios of heterotrophic CO2-fixation during assimilation of acetyl-CoA originating from the contaminant by these degraders. These findings demonstrate that the importance of non-proteobacterial populations in anaerobic aromatics degradation, as well as their specific ecophysiology in the subsurface may still be largely ungrasped.

Original languageEnglish
Pages (from-to)1314-1325
Number of pages12
JournalISME Journal
Issue number10
StatePublished - Oct 2010
Externally publishedYes


  • BTEX
  • Desulfosporosinus
  • SIP
  • anaerobic toluene degradation
  • benzylsuccinate synthase
  • sulfate reduction


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