【作者】 李加强；

【导师】 梁运祥；

【作者基本信息】 华中农业大学 ， 微生物学， 2003， 硕士

【摘要】 木聚糖是自然界存在的可再生的一种植物成分。木聚糖酶能降解木聚糖成木糖或木寡糖。木聚糖酶在饲料、食品、纺织、造纸等行业有着广泛的用途，是现代酶学研究的热点之一。本实验在固体发酵的基础上，进行了适合液体发酵菌株的筛选和工艺的探索，为木聚糖酶液体发酵生产打下基础。通过以木聚糖酶固体发酵高产菌株黑曲霉F27（A.niger F27）为出发菌株，经钴—60诱变，筛选得到适合于液体发酵的菌株L，在5％的麸皮筛选培养基上酶活为1966u／ml。在摇瓶水平上进行了培养基筛选实验，筛选到适合于木聚糖酶发酵主要碳源—玉米芯、主要氮源—蛋白胨、无机盐离子—Mg²⁺、氨基酸—His，还进行了表面活性剂Tween—80的添加量等因素试验。在得到的发酵培养基的基础上，对发酵条件进行优选，发现在pH值5.5、转速220rpm、500ml摇瓶装量为50ml、温度28～30℃下酶活可达到8226u／ml。在摇瓶发酵工艺优化的基础上进行了发酵罐放大试验，并对发酵罐发酵工艺进行了优化，在玉米芯6％、葡萄糖0.5％、蛋白胨1％和尿素0.3％等的改良培养基上，培养条件为：14h内温度为30℃，14h后28℃，消前pH5.5，罐压0.06mpa～0.08mpa通气1：1.0～1.5搅拌100～150rpm基础上，得到酶活为7200u／ml。更多还原

【Abstract】 Xylan is a component of plants that can be recycled in nature. Xylanase is the enzyme family that dehydrates xylan into xylose or oligoxylose. Xlyanase has extensive applications in the industries of feed, food, fabric and papermaking, and has become one of the hot spots of modern enzymology. Fermentation technics optimization and screening of the strain suitable for liquid fermentation were carried out on the basis of solid fermentation. The strain L suitable for liquid fermentation was selected by mutation of Co-60 with the A.niger 27,the xylanase high production strain as starting strain. The xylanase activity of the strain L on the selective medium of 5% wheat bran was 1966u/ml. Optimization of the medium was carried out on the level of flask, corncob, tryptone, Mg2+ and Hisdidane were selected for the production of xylanase. Effects of other factors, such as Tween-80 on the production of xylanase were also ascertained. After the orthonagol design, the optimal medium for the production of xylanase on the level of flask was established. The fermentation condition was also optimized and the xylanase activity reached 8226u/ml. The optimal temperature, pH, rotate speed and charge volume for xylanase production were 28-30℃, pH5.5, 220rpm and 50/500ml, respectively. The optimization of fermentation technics on the level of the jar was also carried out. The optimal medium for xylanase production was composed of 6%corncob, l%treptone and 0.3%urea. The optimal temperature, pH, vessel pressure, aeration rate and rotate speed were 30℃ in the first 14hr and 28℃ after 14hr, pH5.5 before sterilization, 0.06mpa~0.08mpa,l: 1.0-1.5 and 100~150rpm, respectively. The xylanase activity reached 7200u/ml after optimization.更多还原