Xylitol production from D-xylose byCandida guillermondii: Fermentation behaviour

Summary The ability ofCandida guillermondii to produce xylitol from xylose and to ferment individual non xylose hemicellulosic derived sugars was investigated in microaerobic conditions. Xylose was converted into xylitol with a yield of 0,63 g/g and ethanol was produced in negligible amounts. The strain did not convert glucose, mannose and galactose into their corresponding polyols but only into ethanol and cell mass. By contrast, fermentation of arabinose lead to the formation of arabitol. On D-xylose medium,Candida guillermondii exhibited high yield and rate of xylitol production when the initial sugar concentration exceeded 110 g/l. A final xylitol concentration of 221 g/l was obtained from 300 g/l D-xylose with a yield of 82,6% of theoretical and an average specific rate of 0,19 g/g.h.Nomenclature Q_p average volumetric productivity of xylitol (g xylitol/l per hour) - q_p average specific productivity of xylitol (g xylitol/g of cells per hour) - So initial xylose concentration (g/l) - tf incubation time (hours) - Y_P/S xylitol yield (g of xylitol produced/g of xylose utilized) - Y_E/S ethanol yield (g of ethanol produced/g of substrate utilized) - Y_X/S cells yield (g of cells/g of substrate utilized) - specific growth rate coefficient (h^–1) - _max maximum specific growth rate coefficient (h^–1)