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

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. In this work, the genes LBA1719 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 LBA1719 in regulating the lyophilization-survival rate. 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 LBA1719 decreased the expression of genes gapA, gapB, and pgiA in carbohydrate metabolism and dapA, dapB, and dapE in amino acid metabolism, significantly changing the physiological characteristics of S. carnosus and decreasing its lyophilization-survival rate. In summary, overexpression of UGPase accelerated the growth rate of S. carnosus and reduced its lyophilization-survival rates. GapA, gapB, pgiA, dapA, dapB, and dapE 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.