COST-EFFECTIVE BIOPROCESS TECHNOLOGIES FOR PRODUCTION OF BIOFUELS FROM LIGNOCELLULOSIC BIOMASS
Location: National Center for Agricultural Utilization Research
Title: Butanol Production from Wheat Straw by Simultaneous Saccharification and Fermentation Using Clostridium Beijerinckii: Part I-Batch Fermentation
Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 5, 2007
Publication Date: February 1, 2008
Citation: Qureshi, N., Saha, B.C., Hector, R.E., Hughes, S.R., Cotta, M.A. 2008. Butanol production from wheat straw by simultaneous saccharification and fermentation using Clostridium beijerinckii: Part I - batch fermentation. Biomass and Bioenergy. 32:168-175.
Interpretive Summary: Butanol is an important fuel and chemical. It has superior fuel properties than ethanol including higher energy content. Butanol can be produced from agricultural products such as corn, other starchy crops, and lignocellulosic residues using microbial cultures. In order to reduce the cost of butanol production, use of economically available raw materials such as agricultural wastes/residues is recommended. Hence, in this report we attempted to produce butanol from wheat straw employing cutting edge technology. Wheat straw was hydrolyzed to lignocellulosic component sugars (glucose, xylose, arabinose, galactose, and mannose) and fermented to butanol. Successful production of economically available butanol from wheat straw by fermentation will benefit farmers, butanol producing industry, and the United States public. Development of such a fuel by an economically viable process is essential as the gasoline prices are rising steadily.
Five different processes were investigated to produce acetone-butanol-ethanol (ABE) from wheat straw (WS) by Clostridium beijerinckii. 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 gL**-1 ABE was produced, respectively. Processes I-V resulted in productivities of 0.19, 0.14, 0.27, 0.19, and 0.31 gL**-1h**-1, respectively. It should be noted that Process V resulted in the highest productivity (0.31 gL**-1h**-1). In the control experiment (using glucose), ABE productivity of 0.30 gL**-1h**-1 was achieved. These results suggest that simultaneous hydrolysis of WS to sugars and fermentation to butanol/ABE is an attractive option as compared to 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.