The prerequisite for the probiotic effect of lactic acid bacteria is that they could survive the acid stress environment of production and application. In this experiment, the mechanism for the effect of different metal ion pre-stress on the acid-tolerant survival of Lactobacillus was investigated. Scanning electron microscopy, Fourier infrared spectroscopy, and flow cytometry were used to analyze the condition of bacteria after acid treatment, which revealed that different metal ion pre-stress could improve the survival ability of Lactobacillus acidophilus CICC 6074 under low acid conditions by improving cell morphology, mitigating cell membrane damage, and regulating surface protein expression. Furthermore, Tandem Mass Tags (TMT) proteomic analysis revealed that Mn2+ pre-stress showed relatively more superior protective effects on acid tolerance in L. acidophilus CICC 6074 through activation of DNA replication, RNA synthesis, S-layer protein secretion, H+-ATPase enzyme activity, etc. This study will provide new ideas and a theoretical basis for the development and application of lactic acid bacteria.
Keywords: DNA replication; Lactobacillus acidophilus CICC 6074; RNA synthesis; S-layer protein; acid tolerance mechanism; proteomics.