Lactobacillus fermentum MJM60397 was subjected to in vitro safety tests and in vivo probiotic characterization. The MJM60397 strain was susceptible to antibiotics and was found to be non-mucinolytic and non-hemolytic, and does not produce bioamines. In addition, MJM60397 tolerated simulated oro-gastrointestinal conditions and adhered to Caco-2 cells. MJM60397 also exhibited bile salt hydrolase activity and could deconjugate bile acids. The hypocholesterolemic effects of strain MJM60397 were studied in high-fat diet-induced hypercholesterolemic male ICR mice. The mice were fed a high-cholesterol diet (HCD) and were divided into the following three experimental groups: HCD-control (HCD-Con), mice fed with HCD + L. fermentum MJM60397 (HCD-MJM60397), and mice fed with HCD + L. acidophilus ATCC 43121 (HCD-L.ac) as the positive control. Simultaneously, a normal control diet (NCD) group was maintained. After 7 weeks, the total cholesterol and low-density lipoprotein (LDL) cholesterol levels were significantly reduced in the livers of the HCD-MJM60397 mice when compared to those in the HCD-Con and HCD-L.ac mice. Fecal total bile acid content was significantly (P < 0.05) higher in the HCD-MJM60397 group than in the NCD, HCD-Con, and HCD-L.ac groups. Analysis of gene expression revealed higher expression of LDLR gene in the livers of the HCD-MJM60397 and HCD-L.ac mice than in the livers of the HCD-Con mice. These findings show that the hypocholesterolemic effects of the MJM60397 strain were attributable to its bile salt deconjugating activity, which resulted in decreased bile acid absorption and increased excretion of bile acids in the feces. These results indicate that L. fermentum MJM60397 could be developed into a potential probiotic for reducing the serum cholesterol levels.
Keywords: Bile salt hydrolase; Cholesterol-lowering activity; LDL cholesterol; Lactobacillus fermentum; Probiotics.