American scientists are studying butanol, a product of wheat straw

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The Agricultural Research Service (ARS) of the U.S. Department of Agriculture uses Clostridium beijerinckii to convert cellulose biomass into bio-butanol. Bio-butanol (butyl ethanol) can become an important renewable transportation fuel, as it has a higher energy content than ethanol. It can be used in existing gasoline supply and distribution networks, has a higher octane rating, and can be mixed with gasoline in any proportion. It is also a valuable chemical. Bio-butanol can be obtained from any starch source, which is derived from annual crops such as corn, rice, or barley. However, due to constraints on grain prices and the need to balance food and energy products, using lignocellulosic biomass residues is the preferred option. Scientists at the Agricultural Research Institute, as reported in ‘Biotechnology for Fuels and Chemicals’, state that microbial cultures such as Clostridium beijerinckii P260 can utilize the pentose and hexose sugars present in cellulose biomass and convert them into butanol. To reduce the costs of butanol production, researchers hydrolyze straw into lignocellulosic sugars (glucose, xylose, arabinose, galactose, and mannose) before converting it into butanol. The yield of converting wheat straw hydrolysates into butanol is 214% (as stated in the original text), exceeding that of glucose. Wheat straw is pretreated with dilute sulfuric acid and hydrolyzed into monosaccharides using a glucoamylase preparation. Hydrolysis, fermentation, and product recovery are integrated into a single step carried out in a 2.5-liter bioreactor. The pretreated wheat straw is hydrolyzed into glucose, xylose, arabinose, galactose, and mannose, which are then fermented by Clostridium beijerinckii. Increase the fermentation scale, while recovering the product from the fermentation broth using air lift to avoid inhibition by the final product. Fermentation is carried out in a fed-batch mode, lasting for over 500 hours. This study is part of a larger project titled ‘Economically viable bioprocess technologies for the production of biofuels from lignocellulosic biomass’ (http://www.ars.usda.gov/research/publications/publications.htm?seq_no_115=205373), and it shows that it is feasible to produce propylene-butanol from straw in a single reactor. Developing an economically viable fermentation method for wheat straw to produce butanol is beneficial for farmers, butanol manufacturers, and the general public. Due to the continuous rise in gasoline prices, it is necessary to develop economically viable fuel production processes. Recently, DuPont and BP announced that they would cooperate in producing fuel, with bio-butanol making it to the front pages of the news; they pledged that bio-butanol could serve as a substitute for gasoline for a long time to come. Another biotechnology company, Green Biologics, also received substantial funding (855,000 euros) to develop strategies for producing fuel from cellulose biomass. (http://biopact.com/2007/01/green-biologics-awarded-855000-to_22.html)。