Production of Trichoderma longibrachiatum 185 xylanase by coba husk hemucellulose and its application of preparation of the xylooligosaccharides

• Main Authors: Ting-Wen Chen, 陳婷玟
• Other Authors: Chin-Shuh Chen Ph. D.
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/51808471192810357972

碩士 === 國立中興大學 === 食品科學系 === 89 === Hemicellulose, which consists mainly of xylan, is the second most abundant biomass to cellulose in nature. In this study, a potent xylanase-producing strain, Trichoderma longibrachiatum 185, was used to study the medium composition and growth condition for optimal xylanase production in a 5L bench-top fermentor, enzyme properties and the preparation of xylooligosaccharides. The optimal conditions of extracting of hemicellulose from coba husk by NaOH were that using 12 % NaOH at 65℃ for 5 hours or that at 45℃ for 24 hours. Both yield were about 19.7 and 19.0 %, respectively. The better medium composition for xylanase production from T. longibrachiatum 185 were determined as follows: coba husk hemicellulose, 0.025%；corn steep liquor, 1.0%；KH2PO4, 0.2 %；CaCl2, 0.03 %；MgSO4∙7H2O, 0.03 %；Tween 80, 0.2 %；FeSO4∙7H2O, 0.0005 %；MnSO4∙H2O, 0.00016 %；ZnSO4∙7H2O, 0.0014 %；and CoCl2, 0.0002 %. For cultivation condition, pH 6.0, cultivated at 35℃, agitation rate at 130 rpm, and aeration rate at 1.0 vvm were found to be good to enzyme production. A maximum xylanase activity at 21.6 U/ml was obtained after 3 days of incubation under the above conditions. This was 1.6-times than that obtained previously by using oat spelt xylan as the carbon source and a combined nitrogen source. The optimal temperature and pH for the UF-partially purified xylanase of T. longibrachiatum 185 were 55℃ and 6.0, respectively. The major hydrolysis products of either coba husk hemicellulose or oat spelt xylan by the UF- or UF-ammonium sulfate precipitation partially purified xylanase after 24 hours depended upon the ratio of substrate to the amount of enzyme. Xylobiose and xylotriose were the major ones when the amount of xylanase was low, while xylose became apparent if higher amount of enzyme was used. The degree of hydrolysis of coba husk hemicellulose can up to the maximum when the concentration of substrate was 5%, the concentration ratio of enzyme to substrate was 208U/g and the xylanase activity was 20.5 U/ml.