Hydrogen production from high slat medium by co-culture of Rhodovulum sulfidophilum and dark fermentative microflora

Potential of pH decrease is one of the major obstacle in stable operation in coculture of dark- and photo-fermentative bacteria for hydrogen production. In this study, a dark fermentative bacterial consort and acid-tolerant marine photo-fermentative bacterium, Rhodovulum sulfidophilum TH-102, were individual or co-cultured in high salt medium for hydrogen production. All co-cultures produced more hydrogen than the individual culture of photo or dark fermentation. The dark/photo bacterial ratios were 1:5, 1:10, 1:15 and 1:20, respectively. Among the coculture ratios, bacterial ratio 1:10 produced the highest hydrogen yield (1694 ± 21 mL/L). The addition of the photo-fermentative bacterium to the dark fermentation consort stabilized the pH value and decreased the oxidation-reduction potential of the co-culture system and extended the hydrogen production period. Carbon fixation by the photo-fermentative bacterium may play some role in improving the hydrogen yield of the co-culture system.