Aspects of xylitol formation in sugarcane bagasse hydrolysate by Candida guilliermondii in the presence of tetracycline

The bioconversion of xylose into xylitol using pH values of 4.0, 5.5, and 7 .0 and tetracycline concentrations of 20 and 40 mg/L was carried out to ver ify the influence of these parameters on Candida guilliermondii metabolism for xylitol production. Experiments were performed with sugarcane bagasse h emicellulosic hydrolysate (48.5 g/L of xylose) in 125-mL Erlenmeyer flasks, at 30 degrees C, 200 rpm, during 88 h. The results demonstrated that the b ioconversion of xylose into xylitol was significantly influenced by the pH. On the other hand, in media containing 20 or 40 mg/L of tetracycline, this bioconversion was not significantly affected. The best results of xylitol production were obtained in hemicellulosic hydrolysate without tetracycline , at pH 7.0. In these conditions, the maximum specific growth rate was 0.01 4/h and the yield factor of xylitol and volumetric productivity were 0.85 g /g and 0.70 g/L/h respectively. Xylitol and cell growth occurred simultaneo usly.