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

Abstract

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).