(1) Background: This study investigated the impact of in vitro adaptations to acid and bile stress on the cholesterol-lowering activity of the probiotic Lactobacillus kefir M20. (2) Methods: Lactobacillus kefir M20 was extracted from fermented dairy products in Xinjiang, China, and isolated using MRS medium. The lactic acid bacteria were cultured for stress resistance to acid and bile salts and then gavaged into mice for animal experiments. (3) Results: The adaptation to bile stress treatment resulted in a notable enhancement of the cholesterol-lowering capacity of Lactobacillus kefir M20, with reductions of 16.5% and 33.1% in total and non-HDL cholesterol, respectively, compared to the untreated strain. Furthermore, the daily fecal total bile acid excretion was 9.2, 5.4 and 5.0 times higher in the M20-BSA group compared to the HC, M20 and M20-ASA groups, respectively. (4) Conclusions: This study suggests that targeted probiotics have the potential for application in the next generation of functional foods and probiotic formulations aimed at combating hypercholesterolemia.

Some probiotic strains exhibit immunoregulating effect on host. In the present study, Lactobacillus strains isolated from adult fecal sample and traditional fermented milk were assessed for their anti-inflammatory properties by using RAW264.7 cells treated with LPS.The results showed that Limosilactobacillus fermentum-268 and Limosilactobacillus fermentum-299 reduced the overexpression of nitric oxide (NO) and inflammatory factors (IL-1β, TNF-α) in RAW264.7 cells treated by LPS. Furthermore, L. fermentum 268 and L. fermentum 299 inhibited E. coli adhesion on HT-29 cell monolayers and reduced the expression of inflammatory cytokines (IL-8, IL-10, TNF-α) in HT-29 cells induced by E. coli. L. fermentum 268 can significantly increase the expression of Occludin, Claudin-1 and ZO-1 in HT-29 cells. The survival rates of L. fermentum 268 and LGG in simulated gastric fluid were 96.34% and 95.07%, respectively, and 57.52% and 56.70%, respectively. L. fermentum 268 showed high adhesion to HT-29 monolellers with 8.20 ± 1.15 CFU/cell adhesion indices, respectively. L. fermentum 268 do not show hemolytic activity and antibiotic resistence to ampicillin, gentamicin, kanamycin, erythromycin, clindamycin, tetracycline and chloramphenicol. L. fermentum 268 have the potential to be as probiotics. Conclusion: L. fermentum 268 have immunomodulatory functions, enhance the intestinal barrier function of HT-29 cells, and have potential as probiotics.