Effects of the ecological factors on hydrogen production and [Fe–Fe]-hydrogenase activity in Ethanoligenens harbinense YUAN-3

• The maximum biohydrogen production was obtained by the optimized ecological factors.
• The activity of [Fe–Fe]-hydrogenase was enhanced by the optimization.
• The ecological factors have little effect on cell growth.

Hydrogenase is one of the vital rate-limiting enzymes in biohydrogen production metabolism. The activity of hydrogenase impacts the speed of hydrogen production. In the present study, the novel high efficient H2-producing bacterium Ethanoligenens harbinense YUAN-3 was selected for characterization of the relationship between hydrogenase activity and its hydrogen production performance. The effects of the ecological factors of temperature, pH, C/N ratio Mg2+, and Fe2+ concentration on hydrogen production and the activity of hydrogenase were investigated. The activity of hydrogenase decreased quickly after reaching a maximum rate of 2.18 molH2 molGlucose−1 (H2 yield of 1942.5 mL L−1) along with the fermentation process. The highest hydrogenase activity of strain E. harbinense YUAN-3 was optimized under conditions of 35 °C, pH 4.5, and the optimal C/N ratio of 22.4. It was also found that the optimal concentration of 300  mg L−1 MgCl2·6H2O and 300  mg L−1 FeSO4·7H2O were playing key roles in hydrogen production. The highest hydrogen production was improved to 2.62 molH2 molGlucose−1 (H2 yield of 2138.5 mL L−1) with the maximum activity of the hydrogenase 0.352 U mg−1 protein.