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Title (Primary) Metagenome-based metabolic reconstruction revealsthe ecophysiological function of Epsilonproteobacteria in a hydrocarbon-contaminated sulfidic aquifer
Author Keller, A.H.; Schleinitz, K.M.; Starke, R.; Bertilsson, S.; Vogt, C.; Kleinsteuber, S.;
Journal Frontiers in Microbiology
Year 2015
Department ISOBIO; UMB; PROTEOM;
Volume 6
Language englisch;
POF III (all) T41;
Keywords Campylobacterales, sulfur cycling, rTCA cycle, acetate assimilation, anaerobic hydrocarbon degradation, nitrogen fixation, niche adaptation, intermediary ecosystem metabolism
UFZ wide themes RU3;
Abstract The population genome of an uncultured bacterium assigned to the Campylobacterales (Epsilonproteobacteria) was reconstructed from a metagenome dataset obtained by whole-genome shotgun pyrosequencing. Genomic DNA was extracted from a sulfate-reducing, m-xylene-mineralizing enrichment culture isolated from groundwater of a benzene-contaminated sulfidic aquifer. The identical epsilonproteobacterial phylotype has previously been detected in toluene- or benzene-mineralizing, sulfate-reducing consortia enriched from the same site. Previous stable isotope probing (SIP) experiments with 13C6-labeled benzene suggested that this phylotype assimilates benzene-derived carbon in a syntrophic benzene-mineralizing consortium that uses sulfate as terminal electron acceptor. However, the type of energy metabolism and the ecophysiological function of this epsilonproteobacterium within aromatic hydrocarbon-degrading consortia and in the sulfidic aquifer are poorly understood. Annotation of the epsilonproteobacterial population genome suggests that the bacterium plays a key role in sulfur cycling as indicated by the presence of an sqr gene encoding a sulfide quinone oxidoreductase and psr genes encoding a polysulfide reductase. It may gain energy by using sulfide or hydrogen/formate as electron donors. Polysulfide, fumarate, as well as oxygen are potential electron acceptors. Auto- or mixotrophic carbon metabolism seems plausible since a complete reductive citric acid cycle was detected. Thus the bacterium can thrive in pristine groundwater as well as in hydrocarbon-contaminated aquifers. In hydrocarbon-contaminated sulfidic habitats, the epsilonproteobacterium may generate energy by coupling the oxidation of hydrogen or formate and highly abundant sulfide with the reduction of fumarate and/or polysulfide, accompanied by efficient assimilation of acetate produced during fermentation or incomplete oxidation of hydrocarbons. The highly efficient assimilation of acetate was recently demonstrated by a pulsed 13C2-acetate protein SIP experiment. The capability of nitrogen fixation as indicated by the presence of nif genes may provide a selective advantage in nitrogen-depleted habitats. Based on this metabolic reconstruction, we propose acetate capture and sulfur cycling as key functions of Epsilonproteobacteria within the intermediary ecosystem metabolism of hydrocarbon-rich sulfidic sediments.
ID 16874
Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=16874
Keller, A.H., Schleinitz, K.M., Starke, R., Bertilsson, S., Vogt, C., Kleinsteuber, S. (2015):
Metagenome-based metabolic reconstruction revealsthe ecophysiological function of Epsilonproteobacteria in a hydrocarbon-contaminated sulfidic aquifer
Front. Microbiol. 6 , art. 1396