Dominant sugar utilizers in sediment of Lake Constance depend on syntrophic cooperation with methanogenic partner organisms

Nicolai Müller, Benjamin M. Griffin, Ulrich Stingl, Bernhard Schink*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Six strains of novel bacteria were isolated from profundal sediment of Lake Constance, a deep freshwater lake in Germany, by direct dilution of the sediment in mineral agar medium containing a background lawn of the hydrogen-scavenging Methanospirillum hungatei as a syntrophic partner. The numbers of colony-forming units obtained after incubation for more than 2 months were in the same range as those of total bacterial counts determined by DAPI staining (up to 108 cells per millilitre) suggesting that these organisms were dominant members of the community. Identical dilution series in the absence of methanogenic partners yielded numbers that were lower by two to three orders of magnitude. The dominant bacteria were isolated in defined co-culture with M. hungatei, and were further characterized. Growth was slow, with doubling times of 22-28 h at 28°C. Cells were small, 0.5 × 5 μm in size, Gram-positive, and formed terminal oval spores. At 20°C, glucose was fermented by the co-culture strain BoGlc83 nearly stoichiometrically to 2 mol of acetate and 1 mol of methane plus CO2. At higher temperatures, also lactate and traces of succinate were formed. Anaerobic growth depended strictly on the presence of a hydrogen-scavenging partner organism and was inhibited by bromoethane sulfonate, which together indicate the need for a syntrophic partnership for this process. Strain BoGlc83 grew also aerobically in the absence of a partner organism. All enzymes involved in ATP formation via glycolysis and acetyl CoA were found, most of them at activities equivalent to the physiological substrate turnover rate. This new type of sugar-fermenting bacterium appears be the predominant sugar utilizer in this environment. The results show that syntrophic relationships can play an important role also for the utilization of substrates which otherwise can be degraded in pure culture.

Original languageEnglish (US)
Pages (from-to)1501-1511
Number of pages11
JournalEnvironmental Microbiology
Volume10
Issue number6
DOIs
StatePublished - Jun 1 2008

ASJC Scopus subject areas

  • Microbiology
  • Ecology, Evolution, Behavior and Systematics

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