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|標題:||以茭白筍殼半纖維素為碳源生產Trichoderma longibrachiatum 185聚木糖酉每及其在低聚木糖製備上之應用|
Production of Trichoderma longibrachiatum 185 xylanase by coba husk hemucellulose and its application of preparation of the xylooligosaccharides
corn steep liquor
oat spelt xylan
要由聚木糖所構成。本實驗針對一具聚木糖酶活性之真菌(Trichoderma longibrachiatum 185)進行培養條件及聚木糖酶水解特性之探討。包括使用五公升桌上型發酵槽生產聚木糖酶之較適液態培養基組成與條件、酵素性質分析及低聚木糖之製備等。
素為碳源，1.0 %玉米浸漬液為氮源，及部分無機鹽類，在pH 6.0，培養溫度35℃，攪拌速率130 rpm，通氣量1.0 vvm，培養三天，聚木糖酶活性為21.6 U/ml，為以燕麥聚木糖及複合氮源生產聚木糖酶時之1.6倍。
T. longibrachiatum 185聚木糖酶，其最適作用溫度及pH分別為
55℃及pH 6.0。以經UF或再經硫酸銨部分純化之酵素水解茭白筍殼半纖維素或燕麥聚木糖24小時後，主要水解產物視水解條件而定，當酵素用量低時為木二糖及木三糖；反之則有木糖出現。茭白筍殼半纖維素有較大水解度之條件為基質濃度為5%、酵素與基質用量比為208U/g 、酵素活性為20.5 U/ml時。|
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.
|Appears in Collections:||食品暨應用生物科技學系|
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