Tan Haigang, Dong Jian, Wang Guanglu, Xu Haiyan, Zhang Cuiying, Xiao Dongguang
Tianjin Industrial Microbiology Key Laboratory, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, People's Republic of China,
J Ind Microbiol Biotechnol. 2014 Aug;41(8):1275-85. doi: 10.1007/s10295-014-1467-7. Epub 2014 Jun 21.
Several recombinant strains with overexpressed trehalose-6-phosphate synthase gene (TPS1) and/or deleted trehalase genes were obtained to elucidate the relationships between TPS1, trehalase genes, content of intracellular trehalose and freeze tolerance of baker's yeast, as well as improve the fermentation properties of lean dough after freezing. In this study, strain TL301(TPS1) overexpressing TPS1 showed 62.92 % higher trehalose-6-phosphate synthase (Tps1) activity and enhanced the content of intracellular trehalose than the parental strain. Deleting ATH1 exerted a significant effect on trehalase activities and the degradation amount of intracellular trehalose during the first 30 min of prefermentation. This finding indicates that acid trehalase (Ath1) plays a role in intracellular trehalose degradation. NTH2 encodes a functional neutral trehalase (Nth2) that was significantly involved in intracellular trehalose degradation in the absence of the NTH1 and/or ATH1 gene. The survival ratio, freeze-tolerance ratio and relative fermentation ability of strain TL301(TPS1) were approximately twice as high as those of the parental strain (BY6-9α). The increase in freeze tolerance of strain TL301(TPS1) was accompanied by relatively low trehalase activity, high Tps1 activity and high residual content of intracellular trehalose. Our results suggest that overexpressing TPS1 and deleting trehalase genes are sufficient to improve the freeze tolerance of baker's yeast in frozen dough. The present study provides guidance for the commercial baking industry as well as the research on the intracellular trehalose mobilization and freeze tolerance of baker's yeast.
为了阐明海藻糖-6-磷酸合酶基因（TPS1）、海藻糖酶基因、细胞内海藻糖含量与面包酵母耐冻性之间的关系，并改善冷冻后瘦面团的发酵特性，获得了几种海藻糖-6-磷酸合酶基因（TPS1）过表达和/或海藻糖酶基因缺失的重组菌株。在本研究中，过表达TPS1的菌株TL301（TPS1）的海藻糖-6-磷酸合酶（Tps1）活性比亲本菌株高62.92%，细胞内海藻糖含量也有所增加。缺失ATH1对预发酵前30分钟内的海藻糖酶活性和细胞内海藻糖降解量有显著影响。这一发现表明酸性海藻糖酶（Ath1）在细胞内海藻糖降解中起作用。NTH2编码一种功能性中性海藻糖酶（Nth2），在没有NTH1和/或ATH1基因的情况下，它显著参与细胞内海藻糖的降解。菌株TL301（TPS1）的存活率、耐冻率和相对发酵能力约为亲本菌株（BY6-9α）的两倍。菌株TL301（TPS1）耐冻性的提高伴随着相对较低的海藻糖酶活性、较高的Tps1活性和较高的细胞内海藻糖残留量。我们的结果表明，过表达TPS1和缺失海藻糖酶基因足以提高面包酵母在冷冻面团中的耐冻性。本研究为商业烘焙行业以及面包酵母细胞内海藻糖动员和耐冻性的研究提供了指导。
