The function of uridine diphosphate glucose pyrophosphorylase in the lyophilization-stress response of Lactobacillus acidophilus

Purpose Uridine diphosphate glucose pyrophosphorylase (UGPase) plays an important role in glucose metabolism, catalyzing the reversible formation and decomposition of UDP-glucose (UDPG). In previous work, we found that UGPase is a key enzyme in lyophilization response for Lactobacillus acidophilus ( L. acidophilus ). However, its function and regulatory mechanism in the freeze-drying stress response are unknown. Herein, the effect of UGPase on freeze-drying survival rate of Staphylococcus carnosus ( S. carnosus ) was studied. Methods In this work, the genes LBA 1719 encoding UGPase of L. acidophilus ATCC4356 were inserted into plasmid pMG-36e to construct the recombinant plasmid pMG-LBA1719 and then overexpressed in S. carnosus ; the control group was S. carnosus transformed by pMG-36e. The lyophilization-survival rate of overexpressed S. carnosus was determined, and the differentially expressed genes (DEGs) were analyzed by transcriptome to disclose the mechanism of LBA 1719 in regulating the lyophilization-survival rate. Results Compared with the control group, the UGPase activities of the overexpressed S. carnosus increased by 35.49%, while the lyophilization-survival rates decreased by 11.17% ( p < 0.05). Overexpression of LBA 1719 decreased the expression of genes gap A, gap B, and pgi A in carbohydrate metabolism and dap A, dap B, and dap E in amino acid metabolism, significantly changing the physiological characteristics of S. carnosus and decreasing its lyophilization-survival rate. Conclusion In summary, overexpression of UGPase accelerated the growth rate of S. carnosus and reduced its lyophilization-survival rates. Gap A, gap B, pgi A, dap A, dap B, and dap E are vital to lyophilization protection in lactic acid bacteria (LAB). These findings provide new theoretical basis for analyzing the regulatory and molecular mechanisms of lyophilization resistance in LABs.