Probiotic Properties Of Lactobacillus Plantarum K25 And Its Application In Cheese

There are more interesting to lower cholesterol, preventing cardiovascular disease caused by high serum cholesterol level, using lactic acid bacteria. In this study, the probiotic properties of Lactobacillus plantarum K25 isolated from Tibet kefir and its application in cheese were studied, and focused on its cholesterol-lowering effect and the mechanism.(1) L. plantarum K25 could survived in the medium containing 6 mg/mL oxgal or pH=3.0 for 6 h, and had a good tolerance for some antibiotics, for Gentamicin, Kanamycin, Vancomycin et al. L.plantarum K25 could remove 79.7%cholesterol from medium after 24 h incubation at 37℃.(2) The mechanisms of cholesterol removal by L.plantarum K25 in vitro were discussed. The effects of the amount of cholesterol and bile salts added in medium, different bile salts, medium pH and incubation time on cholesterol-lowering effects of L.plantarum K25 were investigated. The results showed that medium pH was the main factor effecting on the cholesterol-lowering activity of L.plantarum K25. As the medium pH decreased to 4.92, L.plantarum K25 removed cholesterol rapidly by adhering cholesterol to its cell surface, based on the fact that 66.7%of cholesterol was found in the ethanol washing solution.(3) Probiotic Cheddar cheese containing L.plantarum K25 was made. After 3 months of ripening at 4℃, the viable count of probiotic bacteria maintained 8.60 Log10CFU/g, higher than the number of probiotic bacteria product requirements. Compared with probiotic cheese and control cheese, there were no significant differences (P> 0.05) in physicochemical indexes, proteolytic degree, amino acid composition, volatile flavor compounds, and texture. The results of Sensory evaluation of cheese showed probiotic cheese containing L.plantarum K25 had no undesirable on taste, and the score slightly higher than control cheese. Based on above conclusions L.plantarum K25 is suitble for probiotic cheese making as adjunct culture.(4)The animal test was used to determine cholesterol-lowering effect of L.plantarum K25 in vivo, the results showed that L.plantarum K25 had no significant effects (P> 0.05) on organ and weight of mice. There was lower serum cholesterol concentration of group fed with high-dose of probiotic cheese than that of group fed with high-dose control cheese, which indicated L.plantarum K25 could reduce 22.5%serum total cholesterol. There no significant effects on anti-atherogenic index or atherosclerosis index of mice observed, but feeding with high-dose of L.plantarum K25 had an active role in the prevention of atherosclerosis.