MAL62 overexpression enhances uridine diphosphoglucose-dependent trehalose synthesis and glycerol metabolism for cryoprotection of baker’s yeast in lean dough

Microbial Cell Factories

Ping Xiao¹  Xi Sun¹  Jun Zhang¹  Hai-Qing Liu¹  Zhi-Hua Fan¹  Wen-Bi Zhu²  Feng Li³ 

[1] College of Biological Engineering, Tianjin Agricultural University, 300384, Tianjin, People’s Republic of China;Tianjin Engineering Research Center of Agricultural Products Processing, 300384, Tianjin, People’s Republic of China;Experiments and Teaching Center for Agricultural Analysis, Tianjin Agricultural University, 300384, Tianjin, People’s Republic of China;Frontier Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, 300072, Tianjin, People’s Republic of China;Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, 300072, Tianjin, People’s Republic of China;

关键词: Saccharomyces cerevisiae;    Trehalose synthesis pathway;    Alpha-glucosidase;    Maltose;    Glycerol;    Freezing tolerant;    RNA-seq;    Lean dough;   

DOI  :  10.1186/s12934-020-01454-6

来源: Springer

【 摘 要 】

BackgroundIn Saccharomyces cerevisiae, alpha-glucosidase (maltase) is a key enzyme in maltose metabolism. In addition, the overexpression of the alpha-glucosidase-encoding gene MAL62 has been shown to increase the freezing tolerance of yeast in lean dough. However, its cryoprotection mechanism is still not clear.ResultsRNA sequencing (RNA-seq) revealed that MAL62 overexpression increased uridine diphosphoglucose (UDPG)-dependent trehalose synthesis. The changes in transcript abundance were confirmed by quantitative reverse transcription–polymerase chain reaction (qRT-PCR) and enzyme activity assays. When the UDPG-dependent trehalose synthase activity was abolished, MAL62 overexpression failed to promote the synthesis of intracellular trehalose. Moreover, in strains lacking trehalose synthesis, the cell viability in the late phase of prefermentation freezing coupled with MAL62 overexpression was slightly reduced, which can be explained by the increase in the intracellular glycerol concentration. This result was consistent with the elevated transcription of glycerol synthesis pathway members.ConclusionsThe increased freezing tolerance by MAL62 overexpression is mainly achieved by the increased trehalose content via the UDPG-dependent pathway, and glycerol also plays an important role. These findings shed new light on the mechanism of yeast response to freezing in lean bread dough and can help to improve industrial yeast strains.

【 授权许可】

CC BY