Xylitol production by Candida species grown on a grass hydrolysate

World J Microbiol Biotechnol (2009) 25:913916 DOI 10.1007/s11274-008-9947-4

SHORT COMMUNICATION

Xylitol production by Candida species grown on a grass hydrolysate

Thomas P. West

Received: 8 November 2008 / Accepted: 17 December 2008 / Published online: 4 January 2009 Springer Science+Business Media B.V. 2009

Abstract Xylitol was produced by selected species of the yeast Candida after growth on a medium containing a hydrolysate of the North American perennial prairie grass big bluestem. The grass was hydrolysed by a combination of dilute acid and enzymatic treatments. After growth on the medium for 120 h at 30 C, Candida tropicalis ATCC 750 produced a 1.4-fold higher level of xylitol than didC. tropicalis ATCC 20215 while biomass production byC. tropicalis ATCC 750 was 1.7-fold higher than Candida guilliermondii ATCC 20216. The xylitol yields observed for C. tropicalis ATCC 750, Candida mogii ATCC 18364 and C. guilliermondii ATCC 20216 were at least 1.4-fold higher than the yield observed for C. tropicalis ATCC 20215 after growth for 120 h at 30 C.

Keywords Biomass Candida Hydrolysate

Xylitol Yield

Introduction

Xylitol is an industrially valuable chemical with a number of commercial applications whose annual commercial production is approaching 40,000 tons (Granstrom et al. 2007). The most important industrial application of xylitol is as an alternate sweetener because of its substantial sweetening power (Edomi 1978). Xylitol also has biomedical applications including being used to prevent ear

inammations and to stimulate murine hybridoma cell production (Petch and Butler 1996; Uhari et al. 1998). The costs to commercially synthesize xylitol are high because the production process involves the catalytic hydrogenation of xylose using a chemical catalyst (Silva et al. 2005). An alternative approach to synthesize xylitol is from the ve carbon sugars released from hydrolysed plant biomass (Zhang 2008). Prairie grasses represent a possible plant biomass that could be utilized. Presently, prairie grasses are utilized for grazing by livestock or harvested as hay for foraging by livestock (Mulkey et al. 2008). These grasses produce a high yield with minimal fertilizer input and they contain a very high ber content indicating a high level of hemicellulose (Mulkey et al. 2008). The perennial grass big bluestem (Andropogon gerardii Vitman) is an example of such a grass (Mulkey et al. 2008). A high concentration of hemicellulose can...