Another chemolithotrophic metabolism missing in nature: sulfur comproportionation.
Environ Microbiol
; 22(6): 1971-1976, 2020 06.
Article
in En
| MEDLINE
| ID: mdl-32157786
ABSTRACT
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 (3H2 S + SO 4 2 - + 2H+ â 4S0 + 4H2 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 (H2 S + SO 4 2 - â S 2 O 3 2 - + H2 O) and to sulfite (H2 S + 3 SO 4 2 - â 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.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Sulfur
/
Bacteria
/
Energy Metabolism
/
Chemoautotrophic Growth
Type of study:
Prognostic_studies
Language:
En
Journal:
Environ Microbiol
Journal subject:
MICROBIOLOGIA
/
SAUDE AMBIENTAL
Year:
2020
Document type:
Article
Affiliation country:
United States