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標題: Trichoderma longibrachiatum 185木聚糖�@之誘導、催化特性暨在製備 低聚木糖上之應用
The Induction and Catalytic Properties of a Xylanase from Trichoderma longibrachiatum 185, and Its Application on the Preparation of Xylooligosaccharides
作者: 葉志崇
Yeh, Chich-Chaung
關鍵字: 聚木糖
Trichoderma longibrachiatum
Trichoderma longibrachiatum
activated charcoal
出版社: 食品科學系
摘要: 摘 要半纖維素為自然界中含量僅次於纖維素之碳水化合物,其主要成份 為聚木糖,目前仍屬低度開發利用。本研究乃針對一株具高聚木糖生產 能力之真菌分離株 (Trichoderma longibrachiatum 185),其所產聚木糖 之酵素純化程度及催化特性進行探討。另外,亦探討以萃取自農產廢棄 物之半纖維素為基質時水解產物之分佈、產物之分離與回收、不同時期乳 糖之添加對酵素誘導之影響、添加不同中段誘導物對酵素誘導之影響及聚 木糖之應用等。本菌株所生產之聚木糖屬於胞外酵素,非醣蛋白。經 膠體過濾層析純化之酵素作用於可溶性聚木糖之水解率以燕麥最高,其次 為櫸木及樺木。另外,作用於燕麥聚木糖之水解產物,以木二糖及木五糖 為主;於櫸木及樺木,則產物以木二糖為主。此酵素無法水解木二糖,以 低聚木糖為基質,僅產生木二糖。推測酵素作用屬內切型,不具轉移活 性,其subsite數目大於六個。色胺酸在酵素之活性或基質鍵結部位占重 要地位。自農產廢棄物萃取之半纖維素經本酵素水解後以膠體過濾法分析 ,有聚木糖含量減少、平均分子量不變、但低聚木糖含量變多等現象。培 養期間添加avicel、a-cellulose、sorbose、乳糖及低聚木糖會提升聚木 糖及纖維素活性,而葡萄糖、木糖等會抑制聚木糖活性。活性碳與 酸洗矽藻土之比例在1:2時吸附低聚木糖之效果最佳,20 % (v/v) 乙醇 可溶離出木二糖,回收率可達55.3 %。製造麵包時加入聚木糖及a-澱粉 ,其體積變大,且組織較鬆軟。關鍵字:聚木糖、低聚木糖、半纖維 素、Trichoderma longibrachiatum、乳糖、誘導物、活性碳、酸洗矽藻 土
AbstractHemicellulose is the second most abundant biomass to cellulose that avilable in nature and consists of xylan. Xylan remains to be a less utilized resources until now. A potent isolated strain, Trichoderma longibrachiatum 185, capable of producing endo-xylanase was used in this study. Some catalytic properties of the enzyme after purification were investigated. In addition, action pattern of the hemicellulose extracted from agricultural wastes, hydrolyzed by the xylanase, the timing of adding lactose, or othThe xylanase purified is a nonglycoprotein and an extracellular enzyme, hydrolysis percentage of soluble xylan from oat spelt by the purified xylanase was the highest, followed by those from beechwood and birchwood xylan. In addition, the predominant hydrolyzed products of oat spelt xylan by the purified xylanase were xylobiose and xylopentaose,only xylobiose could be detected when beechwood xylan、birchwood xylan and xylooligosaccharides were used as substrate. Xylobiose colud not be degraded by the purifThe gel filtration chromatograms of xylanase-treated hemicelluloses from agricultrual waste revealed that the average molecular weights remained constant, while the amount of xylan decreased, which was degraded to xylooligosaccharide and xylose. Addition of avicel, a-cellulose, sorbose and lactose to the culture medium greatly induced the synthesis of the xylanase and cellulase. On the contrary, synthesis of the xylanase was inhibited by the presence of glucose or xylose.Combination of activated charcoal with acid-washed celite (1: 2) was the best choice for adsorption of xylooligosaccharides. Up to 55.3 % of xylobiose could be recovered from the adsorbed sugars by using 20 % (v/v) ethanol as an eluant. Addition of xylanase and a-amylase to the bread dough, led to the production of bread with a bigger loaf volume and softer texture than the untreated one.Keywords: xylanase、hemicellulose、Trichoderma longibrachiatum、lactose、 inducer、xylobiose、xylooligosaccharide、activated charcoal、 acid-washed celite
Appears in Collections:食品暨應用生物科技學系



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