Cross Protection of Lactobacillus delbrueckii subsp. Bulgaricus under Different Environmental Stresses and Analysis of Gene Expression

Lactobacillus bulgaricus is the main strain of fermented daily products, but it is often subjected to various environmental stresses. For revealing the anti-stress protection mechanism, the Lactobacillus delbrueckii subsp. bulgaricus ATCC 11842 was used to determine the sublethal and minimum lethal conditions of bacterial cells under different environmental stresses (acid, salt, bile salt, oxygen, and cold). By comparing the survival rate of bacteria] cells treated with sublethal conditions of different environmental stresses, the cross protective effects of bacterial cells under multiple stress environments were studied. According to the transcriptomics sequencing results of ATCC 11842 strain under acid stress and acid-cold stress, 11 genes related to sugar metabolism, amino acid metabolism, transport system, molecular chaperone, and stress were selected, and the RT-qPCR technology was used to analyze the expression changes of these genes at the transcription level under different environmental stresses. The results show that:: ATCC 11842 strain can significantly improve the survival rate under the minimum lethal conditions after pretreatment with acid stress and oxygen stress sublethal conditions (pH 4.8,40 min ; 15 mmol/L, H2O2, 1 h). Among the 11 genes that respond to acid stress in the ATCC 11842 strain, 10 genes were found to also respond to other different environmental stresses. The expression of LDB_RS02110, LDB-RS00810, LDB_RS04920, LDB_RS05285, LDB_RS00230, LDB_RS06340, LDB_RS05615, LDB-RS01180, LDB_RS06995 and LDB_RS03130 were significantly up-regulated and down-regulated. © 2022 Chinese Institute of Food Science and Technology. All rights reserved.