mal62 基因高表达对工业面包酵母发酵力的影响

Effects of mal62-overexpression on leavening ability of baker's yeast

摘要:

摘要:【目的】构建高麦芽糖利用能力的面包酵母菌株，以期提高面包酵母在不加糖面团中的发酵力，增加经济效益的同时减少成本消耗。【方法】克隆工业面包酵母BY-14 的麦芽糖酶基因mal62，以PGK1 强启动子和终止子为调控元件，以酵母-大肠穿梭型质粒Yep-C 为载体，构建重组表达质粒Yep-CPM，并转化酿酒酵母(Saccharomyces cerevisiae)BY-14，经筛选鉴定获得酵母转化子BYCPM。进行转化子的酶活力、mal62 基因表达水平及发酵力测定，检测目的基因的功能性表达。【结果】工业酵母转化子BYCPM 的最大麦芽糖酶活力比对照菌提高15%－52%，发酵力提高40%，比发酵力提高5.6%。【结论】转化子BYCPM 具有更高的麦芽糖酶活力和更强的抗葡萄糖阻遏能力。并且在不加糖面团中，转化子具有更高的发酵力，可以在更短的时间内获得更大的产气量且消耗更少的碳源。

关键词:关键词:麦芽糖酶，面包酵母，发酵力，麦芽糖代谢

Abstract:

Abstract:［Objective］To increase the leavening ability in the lean dough，the maltose utilization ability of baker's yeast was enhanced． ［Methods］A 1. 7kb PGK1 promoter and terminator were ligated and inserted into vector Yep-C to give the expression plasmid named Yep-CP． Then a 1.7kb DNA fragment containing the open reading frame and terminator of mal62 gene was amplified from Saccharomyces cerevisiae BY-14 by PCR，and inserted into Yep-CP to generate recombinant plasmid Yep-CPM. To express mal62 gene properly in S. cerevisiae，the recombinant expression plasmids Yep-CPM with copper resistance gene as the selection marker for yeast transformation were introduced into S．cerevisiae BY-14． The resulting yeast transformant BYCPM was screened on YEPD with 4 mmol/L CuSO4 and identified by colony PCR．Target protein was detected by qRT-PCR，and the enzyme activities and the leavening ability of the recombinant strain BYCPM were determined to confirm whether functional expression was achieved． ［Results］The maximum maltase activity of recombinant strain BYCPM was 15%－52% higher than that of control strain BY-C.Leavening ability and specific leavening ability of recombinant strain BYCPM were 40% and 5.6% higher than that of the control strain BY-C，respectively． ［Conclusion］The mal62-overexpression was an effective way of increasing the maltase activity and the ability of glucose depression in the baker's yeast.Moreover，recombinant strain BYCPM could further enhance the leavening ability and produce more gas while consume lesser carbon source than the control strain.

Key words:Keywords: maltase，baker's yeast，leavening ability，maltose metabolism