Trace Metal Effect on Hydrogen Production Using C.acetobutylicum

This study was carried out to study the effect of trace metal addition for hydrogen production The results show that this bacterial need a selected nutrient with selected concentration. The optimum parameters for cultivation were at initial pH of 7.0 and temperature of 30°C. Trace metal addition to the new medium showed that only iron enhanced the H₂ yield. The results showed that 25 mgL⁻¹ FeSO₄⋅7H₂O enhanced the hydrogen yield from 391 mLg⁻¹ to 408 mLg⁻¹ glucose utilized with biomass concentration of 1.38 gL⁻¹. Y_P/X of 292 mLg⁻¹ L⁻¹, Y_X/S of 0.276 and Y_H2/s of 0.0364, gave the maximum hydrogen productivity of 81.6 mL L⁻¹ h⁻¹. Magnesium and calcium addition were better for growth and not for hydrogen production. Biomass concentration increases as trace metal increases in the fermentation medium. The highest biomass concentration was 1.65 gL⁻¹ at 1000 mgL⁻¹ FeSO₄⋅7H₂O, 1.47 gL⁻¹ at 1000 mgL⁻¹ MgSO₄⋅7H₂O and 1.73 gL⁻¹ at 500 mgL⁻¹ CaCl₂⋅2H₂O, suggested that all trace metal are necessary for biomass production.