Increase hydrogen production by hydrogen-producing mutant UV-d48 in comparison with wild parent strain Etanoligenens sp ZGX4

Hydrogen production by hydrogen-producing mutant strain UV-d48 was one typical ethanol-type fermentative H₂-producing mutant, which the main metabolic end production was ethanol and acetic acid. Compare to the wild type strain, the activity of hydrogenase of mutant UV-d48 was stronger in course of growth and fermentation. It can evolve hydrogen at stronger ability and a greater rate than that of its parent wild type, namely ZGX4. Resting cells of UV-d48 and Ethanoligenens sp ZGX4 were set up in a batch mode in phosphate buffered saline (PBS) to decouple growth from hydrogen production at the expense of glucose of varying composition. Mutant UV-d48 evolved more hydrogen than ZGX4 at glucose concentrations ranging from 2 mmol/L to 200 mmol/L. The difference in the amount of H₂ evolved by both strains decreased as the concentration of glucose increased. The maximal H₂ yield and H₂-producing rate by strain UV-d48 was 3091.1 mL/L and 54 mL/(hOD_unitL) respectively, at a glucose concentration of 60 mmol/L. With strain ZGX4, the maximal H₂ yield and H₂-producing rate was 2180.2 mL/L and 33 mL/(hOD_unitL) under these conditions, respectively. Experiments using wastewater with certain content molasses yielded similar results. In each case, strain UV-d48 evolved hydrogen at a faster rate than the wild type, showing a possible potential for commercial hydrogen production.