Hydrogen production by different strains of Rhodobacter sphaeroides

Utilisation of solar energy by photosynthetic microorganisms for H-2 production attracts much interest due to unlimited supply of energy. It is important to identify the most effective strain in terms of hydrogen production for the feasibility of the process. Four different strains of Rhodobacter sp. were grown in a water-jacketed cylindrical glass-column photobioreactor under anaerobic conditions. Growth characteristics and hydrogen production rates were determined. Comparison between strains of Rhodobacter sp. was based on hydrogen production rate, its duration and the total volume of gas. The best strain was found to be R. sphaeroides L with a gas production rate of 0.0042 L-H2/h/L-culture and total gas volume of 328 ml in about 90 hours. No H2 gas production was observed for R. sphaeroides ATCC 17023 and R. capsulatus ATCC 23782 under the given experimental conditions. Presence of hydrogenase enzyme was also tested in all strains and relative hydrogenase activities were determined.