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Title: PRODUCTION OF L-ARABITOL FROM L-ARABINOSE BY CANDIDA ENTOMAEA AND PICHIA GUILLIERMONDII

Author
item SAHA, BADAL - 3620-65-00
item Bothast, Rodney

Submitted to: Applied Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: Corn fiber represents a renewable resource that is available in sufficient quantities from the corn wet milling industry to serve as a low cost feedstock for production of fuel alcohol. However, typical corn fiber consists of a variety of sugars which traditional yeast cannot ferment to alcohol. Thus, this research was undertaken to screen yeasts from the ARS Culture Collection for conversion of the corn fiber sugar, arabinose, to a valuable alcohol product, arabitol. Two yeast strains were evaluated in detail and were able to convert 70% of the sugar to arabitol. Arabitol may have food applications for humidity control, as a low-calorie bulking agent, for making biosurfactants, for making edible coatings, as a carrier of pharmaceutical compounds, and for separating chemical compounds.

Technical Abstract: Lignocellulosic biomass, particularly corn fiber, represents a renewable resource that is available in sufficient quantities from the corn wet milling industry to serve as a low cost feedstock for production of fuel alcohol and valuable coproducts. Several enzymatic and chemical processes have potential for the conversion of cellulose and hemicellulose to fermentable sugars. The hydrolyzates are generally rich in pentoses (D-xylose and L-arabinose) and D-glucose. Yeasts produce a variety of polyalcohols from pentose and hexose sugars. Many of these sugar alcohols have food applications as low-calorie bulking agents. During the screening of 49 yeast strains capable of growing on L-arabinose, we observed that 2 strains were superior secretors of L-arabitol as a major extracellular product of L-arabinose. Candida entomaea NRRL Y-7785 and Pichia guilliermondii NRRL Y-2075 produced L-arabitol (0.70 g/g) from L-arabinose (50 g/L) at 34 deg C and pH 5.0 and 4.0, respectively. Both yeasts produced ethanol (0.32-0.33 g/g) from D-glucose (50 g/L) and only xylitol (0.43-0.51 g/g) from D-xylose (50 g/L). Both strains preferentially utilized D-glucose > D-xylose > L-arabinose from mixed substrate (D-glucose, D-xylose and L-arabinose, 1: 1: 1, 50 g/L, total) and produced ethanol (0.36-0.38 g/g D-glucose), xylitol (0.02-0.08 g/g D-xylose) and L-arabitol (0.70-0.81 g/g L-arabinose). The yeasts co-utilized D-xylose (6.2-6.5 g/L) and L-arabinose (4.9-5.0 g/L) from corn fiber acid hydrolyzate simultaneously and produced xylitol (0.10 g/g D-xylose) and L-arabitol (0.53-0.54 g/g L-arabinose).