Monday, July 30, 2007
P14

Xylitol production by Candida species grown on acid-hydrolyzed bluestem grass

Thomas P. West, Biology and Microbiology, South Dakota State University, Box 2104, Brookings, SD 57007

The sugar alcohol xylitol is used commercially as a sugar substitute and is produced by a number of Candida species from xylose. In this investigation, the ability of selected Candida species to synthesize xylitol from xylose released as a result of acid and xylanase hydrolysis of the prairie grass Big Bluestem (Andropogon gerardii) was studied. The species screened were Candida tropicalis ATCC 750, Candida tropicalis ATCC 20216, Candida mogii ATCC 18364, Candida guilliermondii ATCC 20216 and Candida guilliermondii ATCC 201935. Dried samples of ground bluestem grass were subjected to 1% sulfuric acid hydrolysis using sterilization and subsequently treated with a fungal xylanase to release xylose from the hydrolysate. A medium containing the hydrolysate was devised and its pH was adjusted to 5. The Candida strains were grown in the medium at 30oC for 168 hours with aeration following inoculation with yeast cells from cultures grown for 48 hours in the same medium. Using an enzyme assay to measure the xylitol present, it was found that xylitol was synthesized by the five strains utilized in this work. After 168 hours of growth at 30oC, the highest concentration of xylitol was produced by C. mogii ATCC 18364 while the lowest level of xylitol was synthesized by C. guilliermondii ATCC 201935. In summary, an acid hydrolysate of the prairie grass Big Bluestem supported xylitol production by selected Candida species but their ability to synthesize xylitol on the hydrolysate was strain-dependent.

See more of Poster Session 2
See more of Posters

See more of The Annual Meeting and Exhibition 2007 (July 29 - August 2, 2007)