Optimization of hydrogen production by the psychrophilic strain G088

Abstract

In this study, the response surface method with a Box-Behnken design was applied to evaluate the effect of temperature, pH and glucose concentration to optimize hydrogen production by psychrophilic strain G088 ([EU636029], which is closely related to Polaromonas rhizosphaerae [EF127651]). Biohydrogen production was performed in 120 cm3 serological bottles with a production medium containing 2.75 g/dm3 tryptone, 0.25 g/dm3 yeast extract and glucose concentration in the range of 10–40 g/dm3, pH 3.0–8.0 and temperature 13–37 °C. According to the mathematical model, temperature 26.30 °C, pH 6.2 and glucose 25.31 g/dm3 were the optimum conditions for a predict hydrogen production (HP) of 503.34 cm3, a hydrogen production rate (HPR) and hydrogen yield (HY) of 37.91 cm3/dm3/h and 1.93 mol H2/mol glucose, respectively. The linear effect of pH and quadratic effect of temperature, pH and glucose concentration were the most significant terms affecting HP. Otherwise HPR was affected only by the quadratic terms of temperature and glucose concentration, while HY was affected by the linear and quadratic effect of the three factors. The optimal production conditions were experimentally tested by triplicate corroborating the correspondence with the predicted value by the mathematical model. The experimental values for hydrogen production, yield and rate under these conditions were 513 ± 12.48 cm3, 36.5 ± 4.10 cm3/dm3/h and 1.81 ± 0.04 mol H2/mol glucose, respectively.