Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: August 20, 2004
Publication Date: August 20, 2004
Citation: Saha, B.C. 2004. Xylitol production by yeasts: current status and future prospects [abstract]. International Congress on Yeasts. p. 52. Technical Abstract: Xylitol is a natural reduced-calorie sweetener with anticariogenic properties that does not need insulin for its metabolism by diabetics. The production of xylitol by fermentation has become attractive because of the problems associated with its production chemically. Many yeasts possess the enzyme NADPH-dependent xylose reductase (EC 18.104.22.168), which catalyzes the reduction of xylose to xylitol as a first step in xylose metabolism. The initial reactions of xylose metabolism are the major limiting steps. We have studied the production of xylitol from xylose, mixed sugar substrates (xylose, arabinose, glucose), and corn fiber acid hydrolyzate by three yeasts (Candida entomaea, Candida peltata, and Pichia guilliermondii). These yeasts produced 0.43-0.56 g xylitol per g xylose when grown on xylose (50 g/L). They produced ethanol (0.32-0.41 g/g) from glucose (50 g/L) and arabitol (0.55-0.70 g/g) from arabinose (50 g/L). Arabinose had no inhibitory effect on xylitol production by the yeasts. In this presentation, the factors affecting the production of xylitol by these three yeasts, especially by Candida peltata, will be described. The current status, problems, and prospects of developing a cost-effective fermentation process using yeasts for production of xylitol from agricultural residues rich in xylan such as corn fiber, corn cob, corn stover, rice straw, and wheat straw, and future directions of research will be presented.