Microbial conversion of bamboo hemicellulose hydrolysate to xylitol
- PDF / 226,761 Bytes
- 8 Pages / 439.37 x 666.142 pts Page_size
- 15 Downloads / 165 Views
Microbial conversion of bamboo hemicellulose hydrolysate to xylitol Masahiro Miura • Ikuma Watanabe • Yasutaka Shimotori • Masakazu Aoyama Yasuo Kojima • Yoshiaki Kato
•
Received: 7 December 2011 / Published online: 26 September 2012 Ó Springer-Verlag Berlin Heidelberg 2012
Abstract A hemicellulose hydrolysate containing 19 g L-1 xylose was prepared from the culm of bamboo (Phyllostachys pubescens) by hydrolysis with 3 % sulphuric acid with a liquor to solid ratio of 10 (g g-1) at 121 °C for 1 h. After detoxification of the hydrolysate with a commercially available activated char followed by neutralisation with calcium carbonate, the resulting sugar solution was subjected to fermentation using the yeast, Candida magnoliae. The maximum xylitol production (10.5 g L-1) and the maximum xylitol volumetric productivity (0.42 g L-1 h-1) were attained under agitation set at 400 min-1 and aeration rate of 0.67 vvm (volume of air per volume of medium per minute). According to the results, a suitable control of the oxygen supply permits the xylitol formation from bamboo hemicellulose hydrolysate.
Introduction Xylitol, a naturally occurring five-carbon sugar alcohol, has received great attention in the food and odontological industries because of its high sweetening power, great negative heat of dissolution and anticariogenic properties. It is also used clinically as a sucrose substituent for obese people, diabetes and glucose-6-phosphate dehydrogenase (G6PD) deficient population. Xylitol is currently produced by a catalytic reduction in xylose present in the hemicellulose hydrolysates of hardwoods or agroindustrial wastes such as corn cobs. Because the hemicelluloses of hardwoods and agricultural wastes contain other monosaccharide units such as M. Miura I. Watanabe Y. Shimotori M. Aoyama (&) Department of Biotechnology and Environmental Chemistry, Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507, Japan e-mail: [email protected] Y. Kojima Y. Kato Institute of Wood Biomass, Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan
123
516
Wood Sci Technol (2013) 47:515–522
arabinose, galactose, glucose and mannose, extensive separation and purification steps are necessary to remove these contaminants from the hydrolysates before the chemical reduction. The inefficiency of current xylose preparation techniques affects seriously the recovery of xylose from lignocellulosic materials. The yields of xylitol correspond to only 50–60 % of xylan present in the raw materials (Hyvo¨nen et al. 1982), and conventional xylitol production process is therefore relatively expensive (Nigam and Singh 1995). An alternative method for the xylitol production is microbial conversion of xylose in the lignocellulose hydrolysates (Winkelhausen and Kuzmanova 1998). Among the microorganisms that can assimilate xylose, the yeasts belonging to the genus Candida are the best xylitol producers (Onishi and Suzuki 1966; Gong et al. 1981; Meyrial et al. 1991). Bamboos, belonging to the Gramineae, occur in natural
Data Loading...
