产木聚糖酶菌株的筛选及其产酶特性

低聚木糖是最受瞩目的一种低聚糖,它不仅具有极好的双歧杆菌增值活性,选择利用广泛,而且售价也较高。通过对玉米秸秆和玉米芯的成分测定,木聚糖质量分数都在20%以上,很适合作为产木聚糖酶菌株发酵底物。从近200份土样、腐烂的玉米芯、玉米秸秆及牛胃(尤其是瘤胃)、牛粪中分离、筛选、纯化出30株能降解半纤维素并产生明显半纤维素水圈的菌株,通过测木聚糖酶和内切纤维素酶比活力,选出一株产木聚糖酶比活力最高的优良菌株CY8。研究了培养时间、温度、pH、氮源、碳源对菌株产木聚糖酶的影响,最佳的碳源m(麦麸)/m(玉米秸杆)为3∶7,最佳的氮源为尿素。发酵的最佳时间为4d、温度为29℃,木聚糖酶、纤维素酶发酵的最佳起始pH值分别为4.6,5.0。

The Screen of the Xylanase Producing Strain and Its Properties of Enzyme Producing

Xylan is the best popular one of its kinds in that it not only can enhance the activity of Bifidobacterium, but also has the best selectivity,meanwhile, the price is also higher.The mass fraction of xylan content of cornstalk and corncob were more than 20% by ingredient analysis, so the cornstalk and corncob were used as ferment medium. The 30 strains, which were obtained by separating, isolating and purifying from nearly 200 samples of spoiled soil, moldy corncob and cornstalk, cow dung, substances inside cow intestine, cow stomach, all degraded hemicellulose and produced evident hemicellulose hydrolyzed circle. Of the 30 strains the best strain CY8 producting highest enzymatic specific activity is selected by determining specific activity of xylanase and inner-cut celluase. The effects of time, temperature, pH, carbon resource, nitrogen resource on the effect of xylanase by strain CY8 were studied. The results show that the best mass radio of wheat bran to corncob is 3∶7 when used as carbon resource, and the urea is the best nitrogen resource, the optimum time, temperature are 4 d, 29 ℃ respectively. The optimum initial pH of xylanase and celluosase are 4.6, 5.0 respectively.