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.

Anodes Stimulate Anaerobic Toluene Degradation via Sulfur Cycling in Marine Sediments

“…SRB belonging to the families Desulfobulbaceae and Desulfobacteraceae were found in the microbial inoculum and were further enriched in BESs. Members of these families have been described previously as key players during hydrocarbon degradation under sulfate-reducing conditions (62,63). The same families (Desulfobulbaceae and Desulfobacteraceae) have been reported previously to be enriched on anodes during bioelectrochemical benzene degradation in sulfide-rich groundwater (21).…”

Functional Gene Markers for Fumarate-Adding and Dearomatizing Key Enzymes in Anaerobic Aromatic Hydrocarbon Degradation in Terrestrial Environments

“…Dominating desulfobulbal bssA sequence types were also identified in toluene-degrading sulphate-reducing enrichments obtained from less contaminated zones of the BTEX-contaminated Zeitz aquifer, while distinct clostridial bssA sequences were detect- 189 ed in parallel enrichments from highly contaminated zones [Kuppardt et al, 2014]. This has allowed for first insights into possible degrader niche partitioning depending on contamination levels in situ.…”

Lignite biodegradation under conditions of acidic molasses fermentation

“…(Peptococcaceae) grows on a large variety of aromatic compounds including lignite monomers (Vos et al, 2009). Members of the Peptococcaceae generally have been described to be involved in the anaerobic degradation of aromatic compounds under various electron acceptor-reducing conditions and frequently in syntrophic associations (Kuppardt et al, 2014).…”

“…The Bacteroides species and other Bacteroidetes such as the Sphingobacterium species are found in environments contaminated with toluene (Kuppardt et al, 2014) and petroleum (Yu et al, 2014), whereas Flavobacterium are capable of sulfur removal from thiophene, thus participating in coal biodesulfurization processes (Prayuenyong, 2002).…”