Acidogenesis driven by hydrogen partial pressure towards bioethanol production through fatty acids reduction

Abstract

H2 partial pressure drives the reduction of carboxylic acid (short chain fatty acids) formed as primary metabolites in acidogenic fermentation to form bioalcohols. Microbial catalysis under the influence of H2 partial pressure was evaluated in comparison with a reactor operated at atmospheric pressure under identical conditions. Carboxylic acid reduction gets regulated selectively by the influence of elevated pressures and redox conditions, resulting in the formation of alcohols. The non-equilibrium of the intra and extracellular H2 ions causes the anaerobic bacteria to alter their pathways as a function of interspecies H2 transfer. Ethanol production was quantified, as acetic acid was the major carboxylic acid synthesised during acidogenesis. H2 pressure influenced the electrochemical activity which was reflected in the distinct variation of the electron transfer rates and the catalytic activity of redox mediators (NAD+/NADH, flavoproteins and iron-sulphur clusters). The bioprocess depicted in this communication depicted a non-genetic regulation of product formation, understanding the acidogenic metabolism and alternate route for alcohol production.