Evaluation of corncob hemicellulosic hydrolysate for xylitol production by adapted strain of Candida tropicalis

Abstract

A maximum xylose extraction of 21.98g/L was obtained in hydrolysate with a solid to liquid ratio of 1:8 (w/v) at 1% H2SO4 and treated for 30min. The optimized and treated corncob hemicellulosic hydrolysate medium supplemented with (g/L) yeast extract 5.0, KH2PO4 2.0, MgSO4·7H2O 0.3 and methanol 10mL whose pH was adjusted to 4.5 acts as production medium. Under this condition; the adapted strain of C. tropicalis resulted in 1.22-fold increase in xylitol yield and 1.70-fold enhancement in volumetric productivity was obtained as compared to parent strain of C. tropicalis. On concentrating the hydrolysate under vacuum using rotavapor proves to be efficient in terms of improved xylitol yield and productivity over microwave assisted concentration using adapted strain of C. tropicalis. The immobilized cells of C. tropicalis resulted in more than 70% efficiency up to third cycle. The xylitol production could be scaled up to 10L fermentor.