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Progress in Earth and Planetary Science

Table 1 Metabolic reactions for chemolithoautotrophy considered in this study

From: Theoretical constraints of physical and chemical properties of hydrothermal fluids on variations in chemolithotrophic microbial communities in seafloor hydrothermal systems

Energy metabolism

Overall chemical reaction

Identified (I)/cultured (C)

ΔG r° 2, 250(kJ) a

Aerobic reactions

   

  Aerobic methanotrophy

CH4 + 2O2 = CO2 + 2H2O

I and C

-860.7

  Hydrogenotrophic O2 reduction

H2 + 1/2O2 = H2O

I and C

-264.4

  Thiotrophic (H2S-oxidizing) O2 reduction

H2S + 2O2 = SO4 2- + 2H+

I and C

-758.2

  Fe(II)-oxidizing O2 reduction

Fe2+ + 1/4O2 + H+ = Fe3+ + 1/2H2O

I and C

-52.6

Anaerobic reactions

   

  Hydrogenotrophic methanogenesis

H2 + 1/4CO2 = 1/4CH4 + 1/2H2O

I and C

-49.2

  Hydrogenotrophic SO4 reduction

H2 + 1/4SO4 2- + 1/2H+ = 1/4H2S + H2O

I and C

-74.9

  Hydrogenotrophic Fe(III) reduction

H2 + 2Fe3+ = 2Fe2+ + 2H+

I and C

-159.2

  Anoxic methanotrophy with SO4 reduction

CH4 + SO4 2- = HCO3 - + HS- + H2O

I but not yet C

-30.1

  1. aStandard-state Gibbs free energy of the metabolic reactions at 2°C, 250 bar.
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