Butanol production from wheat straw by simultaneous saccharification and fermentation using Clostridium beijerinckii: Part I-Batch fermentation

Five different processes were investigated to produce acetone-butanol-ethanol (ABE) from wheat straw (WS) by Clostridium beijerinckii P260. The five processes were fermentation of pretreated WS (Process I), separate hydrolysis and fermentation of WS to ABE without removing sediments (Process II), simultaneous hydrolysis and fermentation of WS without agitation (Process III), simultaneous hydrolysis and fermentation with additional sugar supplementation (Process IV), and simultaneous hydrolysis and fermentation with agitation by gas stripping (Process V). During the five processes, 9.36, 13.12, 11.93, 17.92, and 21.42 g L−1 ABE was produced, respectively. Processes I-V resulted in productivities of 0.19, 0.14, 0.27, 0.19, and 0.31 g L−1 h−1, respectively. It should be noted that Process V resulted in the highest productivity (0.31 g L−1 h−1). In the control experiment (using glucose), an ABE productivity of 0.30 g L−1 h−1 was achieved. These results suggest that simultaneous hydrolysis of WS to sugars and fermentation to butanol/ABE is an attractive option as compared with more expensive glucose to ABE fermentation. Further development of enzymes for WS hydrolysis with optimum characteristics similar to fermentation would make conversion of WS to butanol/ABE even more attractive.