Statistical optimization of biohydrogen production from sucrose by a co-culture of Clostridium acidisoli and Rhodobacter sphaeroides

Statistically based experimental designs were applied to optimize the fermentation process parameters for hydrogen (H-2) production by co-culture of Clostridium acidisoli and Rhodobacter sphaeroides with sucrose as substrate. An initial screening using the Plackett-Burman design identified three factors that significantly influenced H-2 yield: sucrose concentration, initial pH, and inoculum ratio. These factors were considered to have simultaneous and interdependent effects. A central composite design and response surface analysis were adopted to further investigate the mutual interactions among the factors and to identify the values that maximized H-2 production. The optimal substrate concentration, initial pH, and inoculum ratio of C. acidisoli to R. sphaeroides were 11.43 g/L sucrose, 7.13, and 0.83, respectively. Using these optimal culture conditions, substrate conversion efficiency was determined as 10.16 mol H-2/mol sucrose (5.08 mol H-2/mol hexose), which was near the expected value of 10.70 mol H-2/mol sucrose (5.35 mol H-2/mol hexose). (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.