Optimization of direct cellulose fermentation by mixed bacterial culture using response surface methodology

Bacteria culture used during study was obtained from anaerobic digester sludge from a municipal wastewater treatment plant (Poznan area, Poland). The sludge was pretreated at 100 °C for 15 minutes to promote spore-forming bacteria and inhibit methanogenic activity. Pre-heated sludge was inoculated into the basal medium containing cellulose to enrich bacteria capable of cellulose degradation. Box-Behnken design was employed for optimization of the process parameters. The cellulose concentration (C) (2.7 – 13.5 g/L), phosphate buffer concentration (B) (20 – 100 mM) and temperature (T) (29 – 34 °C) were chosen as three independent variables, while H2 production and cellulose consumption were chosen as the response variables. Regression analysis of the model revealed that the highest cumulative hydrogen production of 2.14 L H2/Lmedium could be obtained at 13.5 g cellulose/L, 79.5 mM buffer and 32.6. °C.