title: Phylogenetic and functional diversity within toluene-degrading, sulphate-reducing consortia enriched from a contaminated aquifer.
abstract: Three toluene-degrading microbial consortia were enriched under sulphate-reducing conditions from different zones of a benzene, toluene, ethylbenzene and xylenes (BTEX) plume of two connected contaminated aquifers. Two cultures were obtained from a weakly contaminated zone of the lower aquifer, while one culture originated from the highly contaminated upper aquifer. We hypothesised that the different habitat characteristics are reflected by distinct degrader populations. Degradation of toluene with concomitant production of sulphide was demonstrated in laboratory microcosms and the enrichment cultures were phylogenetically characterised. The benzylsuccinate synthase alpha-subunit (bssA) marker gene, encoding the enzyme initiating anaerobic toluene degradation, was targeted to characterise the catabolic diversity within the enrichment cultures. It was shown that the hydrogeochemical parameters in the different zones of the plume determined the microbial composition of the enrichment cultures. Both enrichment cultures from the weakly contaminated zone were of a very similar composition, dominated by Deltaproteobacteria with the Desulfobulbaceae (a Desulfopila-related phylotype) as key players. Two different bssA sequence types were found, which were both affiliated to genes from sulphate-reducing Deltaproteobacteria. In contrast, the enrichment culture from the highly contaminated zone was dominated by Clostridia with a Desulfosporosinus-related phylotype as presumed key player. A distinct bssA sequence type with high similarity to other recently detected sequences from clostridial toluene degraders was dominant in this culture. This work contributes to our understanding of the niche partitioning between degrader populations in distinct compartments of BTEX-contaminated aquifers.
authors.affiliation: Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Permoserstraße 15, 04318, Leipzig, Germany, anke.kuppardt@ufz.de.
authors.forename: Anke
authors.initials: A
authors.lastname: Kuppardt
authors.forename: Sabine
authors.initials: S
authors.lastname: Kleinsteuber
authors.forename: Carsten
authors.initials: C
authors.lastname: Vogt
authors.forename: Tillmann
authors.initials: T
authors.lastname: Lüders
authors.forename: Hauke
authors.initials: H
authors.lastname: Harms
authors.forename: Antonis
authors.initials: A
authors.lastname: Chatzinotas
mesh_terms: D001673:Biodegradation, Environmental; D004269:DNA, Bacterial / Q000235:genetics; D020564:Deltaproteobacteria / Q000145:classification* / Q000235:genetics; D017753:Ecosystem; D005798:Genes, Bacterial; D005858:Germany; D060587:Groundwater / Q000382:microbiology*; D059013:Microbial Consortia / Q000235:genetics*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D016999:Sulfur-Reducing Bacteria / Q000145:classification / Q000235:genetics; D014050:Toluene / Q000378:metabolism*; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; D014050:Toluene