Another chemolithotrophic metabolism missing in nature: sulfur comproportionation.

Autor: Amend JP; Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA.; Department of Earth Sciences, University of Southern California, Los Angeles, CA, 90089, USA., Aronson HS; Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA., Macalady J; Department of Geosciences, Pennsylvania State University, University Park, PA, 16802, USA., LaRowe DE; Department of Earth Sciences, University of Southern California, Los Angeles, CA, 90089, USA.
Jazyk: angličtina
Zdroj: Environmental microbiology [Environ Microbiol] 2020 Jun; Vol. 22 (6), pp. 1971-1976. Date of Electronic Publication: 2020 Mar 18.
DOI: 10.1111/1462-2920.14982
Abstrakt: Chemotrophic microorganisms gain energy for cellular functions by catalyzing oxidation-reduction (redox) reactions that are out of equilibrium. Calculations of the Gibbs energy ( ΔG r ) can identify whether a reaction is thermodynamically favourable and quantify the accompanying energy yield at the temperature, pressure and chemical composition in the system of interest. Based on carefully calculated values of ΔG r , we predict a novel microbial metabolism - sulfur comproportionation (3H 2 S + SO 4 2 - + 2H + ⇌ 4S 0 + 4H 2 O). We show that at elevated concentrations of sulfide and sulfate in acidic environments over a broad temperature range, this putative metabolism can be exergonic ( ΔG r <0), yielding ~30-50 kJ mol -1 . We suggest that this may be sufficient energy to support a chemolithotrophic metabolism currently missing from the literature. Other versions of this metabolism, comproportionation to thiosulfate (H 2 S + SO 4 2 - ⇌ S 2 O 3 2 - + H 2 O) and to sulfite (H 2 S + 3 SO 4 2 - ⇌ 4 SO 3 2 - + 2H + ), are only moderately exergonic or endergonic even at ideal geochemical conditions. Natural and impacted environments, including sulfidic karst systems, shallow-sea hydrothermal vents, sites of acid mine drainage, and acid-sulfate crater lakes, may be ideal hunting grounds for finding microbial sulfur comproportionators.
(© 2020 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.)
Databáze: MEDLINE
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