Applications of Lactobacillus acidophilus LA18 in Gut Microbiota Regulation and Immunomodulation

Abstract This study explores the properties and applications of Lactobacillus acidophilus LA18. Isolated and preserved under the code CCTCC NO: M 2022572, LA18 demonstrates significant potential in regulating gut microbiota, modulating immune responses, and producing short-chain fatty acids (SCFAs). This strain effectively inhibits pathogenic bacteria such as Staphylococcus aureus, Escherichia coli, and Salmonella, while promoting beneficial bacteria like Akkermansia. LA18's role in enhancing immune response through cytokine modulation further underscores its therapeutic potential.

1. Introduction Lactobacillus acidophilus is a well-known lactic acid bacterium with significant commercial value, primarily utilized in fermented foods and functional products. The emergence of next-generation probiotics like Akkermansia has highlighted the complex interactions between gut microbiota and host health. This study focuses on the novel strain Lactobacillus acidophilus LA18 and its applications in gut health and immunomodulation.

2. Materials and Methods

2.1 Strain Isolation and Preservation 

Lactobacillus acidophilus LA18 was isolated and preserved under the number CCTCC NO: M 2022572. The strain was stored at the China Center for Type Culture Collection (CCTCC), Wuhan University, China.

2.2 Experimental Procedures 

To evaluate LA18's effects, various in vitro assays were conducted to assess its tolerance to gastric and intestinal conditions, antibiotic sensitivity, and inhibitory effects on pathogenic bacteria. Additionally, its impact on gut microbiota composition and immune response was examined through cytokine level measurements.

3. Results

3.1 Tolerance and Safety 

LA18 displayed high tolerance to artificial gastric and intestinal fluids and sensitivity to multiple antibiotics, indicating its non-resistance and safety for human use.

3.2 Antimicrobial Activity 

The strain effectively inhibited Staphylococcus aureus, Escherichia coli, and Salmonella, significantly reducing their adhesion to HT-29 cells.

3.3 Gut Microbiota Modulation 

LA18 increased the abundance of beneficial bacteria such as Akkermansia and Phocaeicola vulgatus. These changes contribute to a balanced gut microbiota, promoting overall gut health.

3.4 Immunomodulatory Effects 

LA18 modulated immune responses by decreasing pro-inflammatory cytokines IL-1β, IL-6, and TNF-α levels while increasing the anti-inflammatory cytokine IL-10. This dual action helps maintain immune homeostasis and prevent inflammatory conditions.

4. Discussion The findings underscore the multifunctional role of Lactobacillus acidophilus LA18 in enhancing gut health and immune function. Its ability to regulate gut microbiota and modulate immune responses makes it a promising candidate for developing functional foods and therapeutic products.

5. Conclusion Lactobacillus acidophilus LA18 exhibits significant potential in the food and pharmaceutical industries for its probiotic properties. Future research should focus on clinical trials to further validate its health benefits and explore its applications in personalized nutrition and medicine.