Evaluation Of The Potential Probiotic Properties And Immune Regulation Function Of Lactobacillus Strains Isolated From Traditional Fermented Yak Milk

Probiotic strains require investigation to obtain functional products and to satisfy the in-creasing market demand for probiotics. Traditional fermented yak milk is a potential source of probiotic Lactobacillus strains. In our study, depended on evaluation of the potential probiotic properties and immune regulation function of Lactobacillus strains isolated from traditional fermented yak milk that were collected from the pasture region of Gansu, China. The domi-nant Lactobacillus strains were isolated, and their potential probiotic properties were eva-luated with respect to function, technology and safety in vitro. Finally, evaluation immune regulation function of Lactobacillus isolates that isolation in vivo. The fundamental results were as follows:1)Lactobacillus isolates were identified on the basis of their physiological and bio-chemical characteristics. A total of 71 isolates of Lactobacillus were isolated from 12 samples of homemade fermented yak milk, which were collected from different individual households in the pasture region of Gansu, China. The isolates were identified as follows: Lactobacillus plantarum ( 23 strains ), Lactobacillus acidophilus ( 21 strains ), Lactobacillus casei ( 12 strains ), Lactobacillus fermentum ( 7 strains ), Lactobacillus brevis ( 3 strains ), Lactobacillus minor ( 3 strains ), and Lactobacillus curvatus ( 2 strains ).2)The dominant Lactobacillus strains were isolated, and their potential probiotic prop-erties were evaluated with respect to function, technology and safety. Two isolates from tradi-tional Gansu fermented yak milk, E2 and G12, possess all of the requirements of useful pro-biotic candidates, including acidifying and coagulating abilities, high tolerance to acid, bile salts and artificial gastrointestinal conditions, high antimicrobial activity against pathogenic bacteria and a high degree of hydrophobic potential for colonization and adherence to intes-tinal epithelium cells.3)The two isolates was further identified by 16S rDNA gene sequencing analysis. Isolate E2 was identified as Lactobacillus acidophilus and G12 was most homologous to Lactobacil-lus casei. The 16S rDNA gene sequences were submitted to the NCBI GenBank, and the GenBank Accession numbers for the 16S rDNA gene sequences of isolates E2 and G12 are HM 598684 and HM 598683 respectively.4)Taking the in vivo experiment, several little mice are orally taken the live bacillus made from L. casei G12 and L. acidophilus E2 in three dosages with high dose, middle dose and low dose and observed for 30 days. Measure the thymus index and spleen index of the mice, observe the function and ability of immune regulation function. The results showed G12 and E2 would not own the ability of immune regulation function.5)Taking the mice for example, the high and middle dose group of L. casei G12 and L. acidophilus E2 can enhance the ratio of macrophage's phagocytosis, compared with the nega-tive control group were significant differences ( P<0.05 ). The results indicated that L. casei G12 and L. acidophilus E2 may enhance non-specific immune.6)Taking the in vivo experiment, test the content of IFN-γ, IL-12 and IL-10 in the blood serum in the method of ELISA. IFN-γ, IL-12 and IL-10 activity in the low, middle and high dose group of L. casei G12 and L. acidophilus E2 compared with the negative control group were significant differences ( P<0.05 ). The high dose group of L. casei G12 compared with the negative control group were highly significant differences ( P<0.01 ). The results indicated L. casei G12 and L. acidophilus E2 may enchance cell immune in mice.7)sIgA content in the gut of the mice which were fed with high dose, middle dose and low dose L. casei G12 and L. acidophilus E2. The results showed high dose, middle dose and low dose L. casei G12 and high dose, middle dose L. acidophilus E2 were significantly in-creased compared with the mice which were not fed ( P<0.05,P<0.01 ). L. casei G12 and L. acidophilus E2 had a regulation effect on serum hemloysin consent in mice. It meaned serum hemolysin content increased continuously, both were higher than the control group signifi-cantly ( P<0.05 ). The concentration of serum IgM antibodies were significantly increase ( P<0.05 ). The result indicated L. casei G12和L. acidophilus E2 may enhance humoral im-mune in mice.