COMPARISON BETWEEN VARIOUS LIGNOCELLULOSIC HYDROLYSATES AS THE SUBSTRATES FOR THE PRODUCTION OF XYLITOL AND BIOMASS BY CANDIDA UTILIS

摘要

Byconversion of various lignocellulosic hydrolysates (oil palm parenchyma tissues, oil palm fronds, corn cobs and sugarcane bagasse) into xylitol and the production of biomass by Candida utilis ITM 1017 were studied. C.utilis ITM 1017 was grown in the various lignocellulosic hydrolysates (with and without pre-treatment) at 30℃, 200 rpm for 80 hours and the amounts of xylitol and biomass produced were monitored. Pre-treatment was carried out by soaking the lignocellulosic samples in 1 mol/L NaOH followed by delignification using sodium chlorite and acetic acid to produce holocellulose. Hydrolysis was carried out using 1 mol/L trifluoroacetic acid at 121 ℃ for 25 min. Results showed that the concentration of biomass produced by C.utilis ITM 1017 was the highest (7.08 ± 1.16 g/L) in the hydrolysate of oil palm fronds without pre-treatment on the 80th hour of bioconversion whilst the lowest maximum concentration of biomass (3.18 ± 0.17 g/L) was produced from the hydrolysate of sugarcane bagasse with pre-treatment on the 80th hours of bioconversion. In contrast, the highest concentration of xylitol (2.21 ± 0.16 g/L) was produced by C.utilis ITM 1017 after 56 hours of growth in the hydrolysate of sugarcane bagasse without pre-treatment whilst the lowest maximum concentration of xylitol (0.8 ± 0.06 g/L) was produced from the oil palm fronds hydrolysate with pre-treatment, on the 44th hour of bioconversion. Pre-treatment showed significant negative effect (p < 0.05) on the yield of the biomass produced by C.utilis ITM 1017 in all the lignocellulosic hydrolysates. However, for the production of xylitol, pre-treatment exhibited a significant negative effect (p < 0.05) only for the production of xylitol by C.utilis ITM 1017 in the sugarcane bagasse hydrolysate.