Submitted to: Biotechnology and Bioengineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2007
Publication Date: 2/1/2007
Citation: Ezeji, T., Qureshi, N., Blaschek, H.P. 2007. Butanol production from agricultural residues: impact of degradation products on Clostridium beijerinckii growth and butanol fermentation. Biotechnology and Bioengineering. 97:1460-1469. Interpretive Summary: Butanol, a superior fuel than ethanol, can be produced from biomass such as corn, and agricultural residues including corn fiber, corn stover, wheat straw, and rice straw. Butanol can be used in internal combustion engines used in transportation vehicles such as cars, buses, and trucks. Historically, butanol production from biomass comes second to ethanol, and plants producing butanol were operational during World War I and II. Unfortunately, this biological process was ceased to be operational due to economic reasons as the biological process could not compete with butanol production from petrochemicals. The aim of the current project was to produce butanol from corn fiber which is sold for .02/lb as animal feed. Prior to fermentation (a biological process to convert sugars to chemicals using microorganism/s), corn fiber must be hydrolyzed to simple sugars (glucose, xylose, arabinose, mannose, and galactose) to be used by the microorganisms. During the dilute sulfuric acid hydrolysis process, some inhibitors are generated that inhibit the fermentation process. Hence, we attempted to identify those fermentation inhibitors. If the process of conversion of corn fiber to butanol becomes commercial, over 2 billion lb/year of butanol would be produced from approximately 9 billion lb/year of corn fiber (produced annually in the U.S.), thus adding value to corn fiber. This process would benefit the U.S. corn growers and create employment opportunities.
Technical Abstract: During pretreatment and hydrolysis of fiber-rich agricultural biomass, compounds such as salts, furfural, hydroxymethyl furfural (HMF), acetic, ferulic, glucuronic, p-coumaric acids, and phenolic compounds are produced. Clostridium beijerinckii BA101 can utilize the individual sugars present in lignocellulosic (e.g., corn fiber, distillers dry grain solubles (DDGS), etc.) hydrolysates such as cellobiose, glucose, mannose, arabinose, and xylose. In these studies, we investigated the effect of some of the lignocellulosic hydrolysate inhibitors associated with C. beijerinckii BA101 growth and acetone butanol and ethanol (ABE) production. When 0.3 g/L p-coumaric and ferulic acids were introduced into the fermentation medium, growth and ABE production by C. beijerinckii BA101 decreased significantly. Furfural and HMF are not inhibitory to C. beijerinckii BA101; rather they have stimulatory effect on the growth of the microorganism and ABE production.