Xylitol, a five carbon alcohol sugar, is a high value product, due principally to its sweetening power, non-cariogenic and insulin-independent metabolism properties justifies the growing interest in optimizing its production at low cost. Currently, it is mainly produced by chemical reduction of xylose. However, due to environmental concerns and concepts of sustainability, researches are directed towards microbial production of xylitol. The industrially valuable compound has also been exploited in the synthesis of xylitol monoesters, due to their outstanding properties as surfactants and medicaments.
In this respect, a newly isolated strain of Candida from flower bud identified as Candida tropicalis produces 12.11 g/l of xylitol in 60h of incubation under unoptimized conditions. Subsequent optimization, using one variable at a time approach resulted in 30.24g/l in presence of 50.0g/l of xylose in 48h.The effect of activity modifier (methanol) at 1.0ml% yielded 32.36g/l and 64.45g/l in presence of 5.0% and 10.0% xylose respectively. The process was scaled upto a 30L bioreactor with 10.0% initial xylose concentration resulted in 63.35g/l in 84h.
This high valued compound when used for the synthesis of xylitol monoesters resulted in 50.32 and 38.36 % conversion with Butyric and Caproic acid, the short carbon chain fatty acids along with purified crystallized xylitol in presence of Pseudomonas lipase used as a biocatalyst and t-butanol: THF (50: 50 v/v ) in 6h of incubation using Gas Chromatography.
Keywords: Xylitol, process optimization, scale up, monoester synthesis