A tolerant lactic acid bacteria, Lactobacillus paracasei, and its immunoregulatory function

Area of Science:

• Microbiology
• Immunology
• Gastroenterology

Background:

• Probiotic bacteria offer health benefits, including immune system modulation.
• Isolation and characterization of novel probiotic strains are crucial for developing functional foods and supplements.
• Traditional fermented dairy products are rich sources of potentially beneficial microorganisms.

Purpose of the Study:

• To isolate and identify a novel probiotic strain from traditional fermented foods.
• To evaluate the gastrointestinal tolerance and immunomodulatory potential of the isolated strain LP2.
• To investigate the dose-dependent effects of strain LP2 on the immune system in a mouse model.

Main Methods:

• Isolation of bacterial strains from yurts cheese, kumiss, and eN-Lac Capsules.
• Biochemical characterization and 16S rDNA sequence analysis for strain identification.
• In vitro tolerance tests (low pH, bile salt, enzymes) and in vivo immunomodulation assays in ICR mice (carbon clearance, lymphocyte proliferation, NK cell activity, DTH reaction).

Main Results:

• Strain LP2, identified as Lactobacillus paracasei with 99.6% 16S rDNA homology, exhibited high tolerance to low pH, bile salt, pepsin, and trypsin.
• LP2 demonstrated significant enhancement of natural killer cell activity and delayed-type hypersensitivity reaction in mice.
• Lymphocyte proliferation was significantly increased in a dose-dependent manner, indicating a positive immunoregulatory effect.

Conclusions:

• The isolated strain LP2 is a robust Lactobacillus paracasei with excellent tolerance to harsh gastrointestinal conditions.
• Strain LP2 possesses significant immunomodulatory properties, enhancing both innate and adaptive immune responses.
• LP2 holds potential as a valuable probiotic ingredient for functional foods aimed at boosting immune health.