The SlpX protein plays a crucial role in the intestinal juice tolerance of Lactobacillus acidophilus CICC6074

The survival ability of lactic acid bacteria (LAB) in the gastrointestinal tract is low, and the mechanism of LAB resistance to the gastrointestinal tract's harsh environment is unclear. Therefore, this study used simulated gastrointestinal juices in vitro and transcriptomics approaches to identify proteins in Lactobacillus acidophilus CICC6074 that can enhance the strain's tolerance to gastrointestinal juices and verify the function of the target proteins. The results showed that the survival rate of Lactobacillus acidophilus CICC6074 was 79.24% after 6 h of in vitro intestinal juice treatment, and there were 10 genes coding proteins with significant changes in expression, among which S-layer protein gene slpX was significantly up-regulated. After overexpression of the slpX gene, the survival rate of Lactobacillus acidophilus CICC6074 was 94.35% after 6 h of in vitro intestinal juice tolerance. In conclusion, the SlpX protein plays a crucial role under the simulated intestinal juice condition of Lactobacillus acidophilus CICC6074. This study provides a basis for a deeper understanding of the survival mechanisms of Lactobacillus acidophilus in the gastrointestinal tract.