Optimization of Culture Conditions for Hydrogen Production by an Anaerobic Bacteria Strain on Soluble Starch Using Response Surface Methodology

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Bio-hydrogen is a clean source of energy with no harmful by-products produced during its combustion so hydrogen is potentially sustainable energy carrier for future. Therefore, bio-hydrogen produced by anaerobic bacteria in dark fermentation has attracted worldwide attention as renewable energy. However, capability of hydrogen production of these bacteria depends on major factors as substrates, iron-containing hydrogenase, reduction agent, pH and temperature. In this study, the Response Surface Methodology (RSM) with Central Composite Design (CCD) was employed to improve hydrogen production of a hydrogen-producing anaerobic bacteria strain that was isolated from animal waste in Phu Linh, Soc Son, Vietnam (PL strain). The hydrogen production process was investigated as a function of three critical factors: soluble starch concentration (8-12 g L-1), ferrous iron concentration (100-200 mg L-1) and L-cysteine concentration (300-500 mg L-1). RSM analysis showed that all three factors had significant influences on the hydrogen production. Among them, ferrous iron concentration presented a greatest influence. The optimum hydrogen concentration of 1030 ml/L medium occurred with 10 g L-1 of soluble starch, 150 mg L-1 of ferrous iron and 400 mg L-1 of L-cysteine after 48 hour- anaerobic fermentation. The hydrogen concentration that produced by the PL strain had increased to two times after using RSM. The obtained results indicated that RSM with CCD can be used as a technique to optimize culture conditions for enhancement of hydrogen production by the selected anaerobic bacteria strain. The production of hydrogen from low-cost organic substrates as soluble starch using anaerobic fermentation methods may be one of the most promising methods.