常压室温等离子诱变选育β-环糊精葡萄糖基转移酶高产菌株及发酵工艺研究

Study on high-yield strains producing β-cyclodextrin glycosyltransferase by atmospheric room temperature plasma mutation breeding and optimization of their fermentation conditions

中文关键词:  β-环糊精葡萄糖基转移酶  常压室温等离子诱变  菌株选育  发酵  酶活力

英文关键词:β-cyclodextrin glycosyltransferase  atmospheric room temperature plasma mutation  strain breeding  fermentation  enzyme activity

中文摘要:

      目的 以嗜碱芽孢杆菌(Bacillus alcalophilus)为出发菌株, 利用常压室温等离子体快速诱变技术筛选β-环糊精葡萄糖基转移酶高产菌株, 并对其发酵工艺进行优化。方法 采用平板菌落透明圈大小结合摇瓶发酵酶活测定进行菌株筛选和发酵工艺优化。结果 筛选出一株遗传稳定性好的β-环糊精葡萄糖基转移酶高产突变株HX188, 在5 m3发酵罐装料系数为55% 的条件下, 经连续6代发酵生产试验, 发酵周期平均为40 h, 产酶水平可稳定在6302 U/mL左右, 较出发菌株2803 U/mL提高了124.8%; 其最佳发酵工艺条件为: 玉米淀粉2%, 豆粕粉5%, pH 8.7, 温度37 ℃, 溶氧水平为20%, 适时流加玉米淀粉、氮源和乳糖可提高菌体浓度及β-环糊精葡萄糖基转移酶酶活力。结论 筛选出的突变株HX188遗传稳定性好, 产酶能力强, 能够满足工业化生产的需要。

英文摘要:

      Objective With basophilic Bacillus (Bacillus alcalophilus) as starting strain, the high-yield strains producing β-cyclodextrin glycosyltransferase were selected by atmospheric room temperature plasma mutation, and the fermentation process was optimized. Methods The screening of strains and fermentation process optimization were conducted by using transparent circle plate colony size and enzyme activity determination in shaking flask fermentation. Results A high-yield mutant strain HX188 producing β-cyclodextrin glycosyltransferase was selected. In 5 m3 fermentor with loading coefficient was 55%, the 6 generations of continuous fermentation experiment was conducted, and the average fermentation time was 40 h. As a result, the enzyme production levels could be stabilized at about 6302 U/mL. Compared with the enzyme production level of starting strain which was 2803 U/mL, the enzyme production level of mutant strain HX188 increased by 124.8%. The optimal fermentation conditions were as follows: corn flour was 2%, corn starch was 5%, pH value was 8.7, temperature was 37 ℃, dissolved oxygen level was 20%, and the cell concentration and activity of β-cyclodextrin glycosyltransferase could be increased by adding corn starch, nitrogen source and lactose timely. Conclusion The mutant strain HX188 has good genetic stability and strong enzyme production capacity, which can meet the needs of industrial production.