Hydrogen production and end-product synthesis patterns by Clostridium termitidis strain CT1112 in batch fermentation cultures with cellobiose or α-cellulose

Hydrogen (H-2) production and end-product synthesis were characterized in a novel, mesophilic, cellulolytic, anaerobic bacterium, Clostridium termitidis strain CT1112, isolated from the gut of the termite, Nasutitermes lujae. Growth curves, pH patterns, protein content, organic acid synthesis, and H-2 production were deter-mined. When grown on 2 gl(-1) cellobiose and 2 gl(-1) alpha-cellulose, C. termitidis displayed a cell generation time of 6.5 h and 18.9 h, respectively. The major end-products synthesized on cellobiose included acetate, hydrogen, CO2, lactate, formate and ethanol, where as on cellulose, the major end-products included hydrogen, acetate, CO2 and ethanol. The concentrations of acetate were greater than ethanol, formate and lactate on both cellobiose and a-cellulose throughout the entire growth phase. Maximum yields of acetate, ethanol, hydrogen and for-mate on cellobiose were 5.9, 3.7, 4.6 and 4.2 mmol l(-1) culture, respectively, where as on cellulose, the yields were 7.2, 3.1, 7.7 and 2.9 mmol l(-1) culture, respectively. Hydrogen and ethanol production rates were slightly higher in C. termitidis cultured on cellobiose when compared to alpha-cellulose. Although, the generation time on a-cellulose was longer than on cellobiose, H-2 production was favored corresponding to acetate synthesis, thereby restricting the carbon flowing to ethanol. During log phase, H-2, CO2 and ethanol were produced at specific rates of 4.28, 5.32, and 2.99 mmol h(-1) g dry weight(-1) of cells on cellobiose and 2.79, 2.59, and 1.1 mmol h(-1) g dry weight(-1) of cells on alpha-cellulose, respectively. (C) 2008 Published by Elsevier Ltd on behalf of International Association for Hydrogen Energy.