Anaerobic biohydrogen production at the thermodynamics limits for atp biosynthesis

Professor Vincent Gray will present his inaugural lecture on the above topic.

 Under dark anaerobic thermophilic conditions the maximum efficiency for biohydrogen generation by a single or multi-species bacterial culture is constrained by thermodynamic conditions to four moles of hydrogens (H2) per mole of glucose.

However, our laboratory has demonstrated that under certain operational conditions an anaerobic multi-species bacterial consortium in a fluidized bacterial granular bed bioreactor can generate more than four moles of hydrogen per mole of glucose.

Partitioning of dissolved hydrogen between mobile solid, liquid and gaseous phases creates conditions which are thermodynamically favourable for the reduction of protons by syntrophic bacteria in the absence of methanogens.

The explanation for this phenomenon is based on the hypothesis that if the actual Gibbs free energy for the coupling of syntrophic proton reduction with the anaerobic oxidation of acetate, propionate and butyrate is not less negative than -20 kJ/mol then ATP can be synthesized, and biohydrogen production will reach efficiencies that exceed four moles of H2 per mole of glucose.

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