39. Clean Energy Technology Development: Hydrogen Production by Escherichia coli During Glycerol Fermentation

Hydrogen (H₂) is accepted as a clean, effective, and renewable energy source; the biotechnology of its production is intensively developed. Glycerol can serve as a cheap carbon source to produce H₂ and the other biofuel by Escherichia coli during mixed acid fermentation. Data on metabolic pathways of glycerol fermentation, hydrogenase enzymes responsible for H₂ production, and dependence of H₂ production on pH and other external factors during glycerol fermentation are summarized; some novel findings are presented. Metabolic engineering to enhance H₂ yield from glycerol has resulted in effective strains. The mixed carbon (glycerol and glucose) fermentation is a novel approach to improve H₂ production and to enlarge carbon sources containing wastes used: glycerol added to glucose-containing medium is shown to increase H₂ production. Taken together these are of significance for improving H₂ production biotechnology as clean energy technology.