Strategy for enhancing photo-hydrogen production yield by repeated fed-batch cultures

In order to obtain the high H2 yield, photo-hydrogen production by Rhodopseudomonas faecalis strain RLD-53 in fed-batch culture using acetate as the sole carbon was studied. In repeated fed-batch culture, biomass increased rapidly from 0.05 to 0.65 g/l within 120 h, with the specific maximal growth rate estimated 0.68 × 10−3 g/h. After 120 h, biomass increased slowly and after each time feeding biomass increased slightly. The specific cumulative H2 volumes in each phase were 2791.3, 1161.7, 1445.5 and 840.6 ml H2/l-culture, respectively. The average H2 yield was 3.17 mol H2/mol acetate based on the whole process while the average substrate conversion efficiency reached 79.3%. Specific maximum H2 production rate and H2 content was 37.2 ml H2/l/h and 95.5%, respectively. The results demonstrated the repeated fed-batch mode obtained higher efficiency for hydrogen production, feeding acetate concentration and control of pH were important to fed-batch culture hydrogen production.