产果聚糖蔗糖酶重组枯草芽孢杆菌的构建及表达

Construction and Expression of a Recombinant Bacillus subtilis Producing Levansucrase

摘要:

果聚糖蔗糖酶能够将蔗糖和乳糖转化为具有益生元功能的低聚乳果糖。为了实现果聚糖蔗糖酶在重组枯草芽孢杆菌中的高效表达，将两种启动子比较并进行串联操作，确定生产果聚糖蔗糖酶的最佳启动子并对重组菌的生长条件进行探索。构建WB-PH、WB-P、WB-H、1A-PH、1A-P、1A-H六种重组枯草芽孢杆菌，其中WB-PH发酵酶活明显优于其他重组菌。研究生长条件对重组菌WB-PH产酶的影响，采用大豆蛋白胨作为氮源，果聚糖蔗糖酶的表达量明显增加，发酵过程中保持较高的溶氧水平也对产酶量有较大的提高。优化后的发酵酶活最高可达108.34 U/mL，相比优化前提高了25.92倍。

Abstract:

Lactosucrose is a rare trisaccharide with prebiotic effect，which can be formed from lactose and sucrose by levansucrase. In this study，levansucrase expression was efficiently carried out by comparing two different promoters and making them tandem. Six different strains with different promoters had been successfully constructed，including WB-PH，WB-P，WB-H，1A-PH，1A-P，1A-H. Amongst them，WB-PH exhibited a higher production level. The effect of growing condition on WB-PH was studied. Using soy peptone as nitrogen source and a higher dissolved oxygen level can enhance levansucrase expression. The enzyme activity reached 108.34 U/mL，which was 25.92 times higher than it before optimization.