iTRAQ‐based quantitative proteomic analysis of the effect of heat shock on freeze‐drying of Lactobacillusacidophilus ATCC4356

Summary In order to investigate the mechanism by which heat shock improves the survival rate of lactic acid bacteria (LAB) following lyophilisation, we performed proteomic analysis based on isobaric tags for relative and absolute quantitation (iTRAQ) on Lactobacillus acidophilus (LA) ATCC4356. Among the 75 differentially expressed proteins (DEPs), 16 and 59 were up‐ and downregulated, respectively, mainly related to amino acid metabolism, glycolysis, ABC transportation, transcription and translation. Mrn C, tuf , rec G, ych F, pur B, dtp T, LBA1220 , LBA0434 and LBA0921 were identified as key genes mediating tolerance to freeze‐drying. Energy supply was enhanced by regulating amino acid metabolism and glycolysis, while energy consumption was decreased by downregulating most translation‐related proteins. DNA and the cellular internal environment were stabilised, and ABC transporters assisted adaptation to freeze‐drying. The results provide new insight for understanding tolerance to freeze‐drying in LAB following heat shock treatment.