Effects of vitamins (nicotinic acid, vitamin B1 and biotin) on phototrophic hydrogen production by Rhodobacter sphaeroides ZX-5

The effects of vitamins (nicotinic acid, vitamin B1 and biotin) on the growth and hydrogen production of Rhodobacter sphaeroides ZX-5 were investigated by batch culture in this study. The results showed that nicotinic acid, as a precursor of NAD+/NADH, plays a crucial role in effectively enhancing the phototrophic hydrogen synthesis during photo-fermentation process. Lack of nicotinic acid in hydrogen production medium resulted in the failure of photo-hydrogen production. In addition, though vitamin B1 and biotin do not have direct impact on photo-hydrogen production, they are still essential and must exist in either growth medium or hydrogen production medium. Without either of them, photo-hydrogen production decreased seriously, regardless of the existence of nicotinic acid.