Optimation xilitol production with variation of sugar cane bagasse hemicellulose hydrolysate concentration by Candida tropicalis

Abstract

Abstract. The aims of this research were to study the growth of C. tropicalis, the optimization of xylitol production, and the efficiency of xylitol production by varying the concentration of sugarcane bagasse hemicellulose hydrolysate. The framework of this research was bioconversion xylose into xylitol by C. tropicalis influenced substrate concentration in production medium. Using different sugar cane bagasse hemicellulose hydrolysate concentrations could as the optimum sugar cane bagasse hemicellulose hydrolysate concentration on xylitol production by introducing C. tropicalis. The methods used in this experiment were as follow: sugarcane bagasse was hydrolyzed by H₂SO₄ 0.035 M in an autoclave at 121°C, 2 atm for 20 minutes. The liquid fraction was concentrated at 50°C using a rotary evaporator. The hydrolysate was neutralized with Ca(OH)₂ to a pH of 10 and then removed by centrifugation at 2000 rpm for 20 minutes. The hydrolysate was added with H₂SO₄ to a pH 6.5 and then removed by centrifugation at 2000 rpm for 20 minutes and sterilized by autoclaving at 121°C for 15 minutes. Sugarcane bagasse hemicellulose hydrolysate concentration was variated from 10%, 20%, and 30% and used as substrate in the production medium. The bioconversion process by C. tropicalis lasted for 4 days. Parameters used in this experiment were biomass of C. tropicalis measured by hemacytometer, xylose, and xylitol concentration in the sugar cane bagasse hemicellulose hydrolysate, and production medium was analyzed by High-Performance Liquid Chromatographic (HPLC). The results showed that: the growth of C. tropicalis lasted for 4 days of cultivation increased in every variation of sugar cane hemicellulose hydrolysate concentration. The optimum xylitol production founded in production medium contained 20% sugar cane bagasse hemicellulose hydrolysate in the third day’s cultivation with xylitol production 10.258 g/l, yield 0.22 g/g and biomass of C. tropicalis 2.9 x 10⁸ cell/ml; The optimum efficiency of xylitol production from sugar cane bagasse hemicellulose hydrolysate by C. tropicalis was 24.21% in 20% sugar cane bagasse hemicellulose hydrolysate in the third day’s cultivation.