| Summary: | 碩士 === 國立中興大學 === 食品科學系 === 87 === Abstract
Hemicellulose is the second most abundant biomass to cellulose that available in nature and consists largely of xylan. Xylan remains to be a less utilized resource until now. A potent isolated strain, Trichoderma longibrachiatum 185, capable of producing endoxylanase was used in this study. The objectives of this study are to determine the effects of combined adding combination of non-xylan compounds, avicel,sorbose and cellulose, to a medium with or whithout oat spelt xylan on the production of xylanase and CMCase by Trichoderma longibrachiatum 185； and to purify the enzymes induced. In addition, effects of various sources of organic nitrogen on the xylanase produced by Trichoderma longibrachiatum 185 was also studied.
When T. longibrachiatum 185 was grown on the Mandels-Reese medium with oat spelt xylan as a carbon source, the activities of both xylanase and CMCase induced were 9.4 and 2.1 U/ml, respectively； however, the respective enzyme activities were increased to 11.8 and 4.5 U/ml when the xylan was replaced by a combination of sorbose (0.8%)+avicel (0.1%)+cellulose (0.1%). The purified enzymes after CM-Sepharose CL-6B and Sephacry S-200 HR chromatographies on SDS-PAGE appeared two bands of enzyme, and the molecular weights of the enzymes were endoxylanase (18.6kDa) and endoglucanase (60.1kDa), respectively. The pI value of endoglucanase and endoxylanase were 3.8 and pI≧9.3, respectively. The endoglucanase was stable at temperatures up to 60℃ and the action mode was endo-type. The optimale pH of endoglucanase was pH4~5. The predominant hydrolyzed products of oat spelt xylan by the purified endoglucanase were xylobiose and xylose, and of hemicellulose of tabacco stalk were xylobiose and xylose.
Growth of Trichoderma longibrachiatum 185 on several kinds of organic nitrogen source, the soybean meal and soy protein sustained better growth and production than other source tested.
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