Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2004
Publication Date: 4/1/2004
Citation: Saha, B.C., Iten, L.B., Cotta, M.A., Wu, Y. 2004. Fuel ethanol production from wheat straw: current status and technical prospects [abstract]. Second World Conference and Technology Exhibition on Biomass for Energy, Industry, and Climate Protection. Paper No. OC2.5.
Technical Abstract: In the USA, the production of fuel ethanol from corn starch reached about 2.1 billion gallons in 2002. Recent legislation requires the use of at least 5 billion gallons a year of corn based ethanol by 2012. Developing ethanol as fuel, beyond its current role as a fuel oxygenate, will require developing lignocellulosic biomass as a feedstock because of its abundance and low cost. In many countries, including the U.S., wheat straw is an abundant byproduct from wheat production. It contains about 35-40% cellulose, 20-30% hemicellulose, and 8-15% lignin and can serve as a low-cost attractive feedstock for production of fuel alcohol. Currently, the use of wheat straw to produce fuel ethanol faces significant technical and economic challenges. Its success depends largely on the development of an environmentally friendly pretreatment procedure, highly effective enzyme systems for conversion of pretreated wheat straw to fermentable sugars, and an efficient microorganism to convert multiple sugars to ethanol. Pretreatment of any lignocellulosic biomass is crucial before enzymatic saccharification. We have evaluated hot water, dilute acid at varied temperatures (120-180 deg C), and alkali as pretreatment options of wheat straw. Dilute acid pretreatment at 160 deg C and above produces fermentation inhibitors such as furfural and hydroxymethyl furfural. The effects of some additives such as zinc chloride, ethylene carbonate, and maleic acid on dilute acid pretreatment of wheat straw will be presented. Pretreated wheat straw was almost completely saccharified to component sugars by various commercial enzyme (cellulase, beta-glucosidase, hemicellulase, and pectinase) preparations. Our research unit has developed a recombinant Escherichia coli (strain FBR5; Dien BS, Nichols NN, O'Bryan PJ, Bothast RJ. Appl. Biochem. Biotechnol. 84/86: 181-186, 2000) that can ferment multiple sugar substrates to ethanol. The results of alcohol production by this recombinant bacterium from various pretreated and enzyme saccharified wheat straw hydrolyzates will be presented. Fuel ethanol was produced from both acid and alkali pretreated wheat straw using a simultaneous saccharification and fermentation (SSF) approach. The effect of detoxification of acid treated hydrolyzates using lime will also be presented. This presentation will feature a comprehensive progress report on our efforts on converting wheat straw to fuel ethanol. The current status, problems, and prospects of developing an environmentally friendly cost-effective bioprocess technology for converting wheat straw to bioethanol will be discussed.