Lactobacillus Plantrum KF5 Screening And Primary Study On Its Cholesterol-Reducing Characteristics

According to the latest census, heart disease is the number one cause of death in many countries. Reduction of total plasma cholesterol can lower the incidence of coronary heart disease in that people suffering from primary hypercholesterolemia. Several studies have indicated that some Lactic acid bacteria can reduce cholesterol. To investigate cholesterol-reducing effect of Lactobacillus plantrum KF5 strain, our research focuses on as follows:The cholesterol-reducing ability was tested on 56 strains of lactic acid bacteria isolated from Tibet kefir grain and 9 strains of lactic acid bacteria stored in our lab by the o-phthalaldehyde method. Lactobacillus plantarum KF5 strain was screened out for its best cholesterol-reducing ability and bionomics. Its cholesterol-reducing rate was (34.56±1.85) % in the MRS-CHOL culture.The viability count of KF5 strain after incubated in the acid MRS culture and bile salt MRS culture designed to simulate human gastrointestinal tract condition were determined. The results showed that KF5 strain had good acid tolerance and bile salt tolerance so that it could be successfully reach the intestine through the gastric acid environment.Composition and contents of fatty acids and partial organic acids in the fermented culture of KF5 strain were determined. As shown from the results, the fermented culture has diverse unsaturated fatty acids. In addition, acetic acid and lactic acid were dominant metabolic products among the organic acids in the fermented culture. Their content were 44.78mg/mL and 3.91 mg/mL respectively.The influence on the cholesterol-reducing ability in vitro by KF5 strain was studied in the different conditions in the MRS-CHOL cultures. The results showed that the cholesterol-reducing rate by KF5 strain increased with the increase of incubation time. The strain that grown in the presence of sodium taurocholate is more reductive than that grown in the absence. Along with the increase of concentration of sodium taurocholate and cholesterol, and with the decrease of pH value, cholesterol-reducing rate firstly increasing and later decreased. Polydextrose had positive effect on the cholesterol-reducing.The cultureB included KF5 strain, Lactobacillus bulgaricus and Streptococcus thermophilic. The cholesterol-reducing rate in the cultureB-fermented milk was (14.27±0.67)%. It's apparently higher than that of common culture A (P < 0.05).Viability count was more than 10~6cfu/mL in the fermented milk stored at 4℃after 20 days. The viscosity was 1203mPa·s. Whey extracting rate was lower. And postacidification of fermented milk was inhibited. So KF5 strain could be applied to the production of low-cholesterol fermented milk.KF5 strain had good hypolipidemic effect on hyperlipemia of SD mice. After treatment with KF5 strain, serum total cholesterol, triglyceride, low-density lipoprotein cholesterol, liver and faeces total cholesterol, triglyceride of hyperlipemia of SD mice were less than that of the control (P < 0.05). Viable count of Bifidobacterium increased in the faeces (P < 0.05). Bifidobacterium and lactic acid bacteria increased as well as Escherichia coli reduced in the cecum (P < 0.05). And Escherichia coli, Bifidobacterium and lactic acid bacteria all increased in the colon (P < 0.05). Organic acids increased in the faeces and propanoic acid was the most obvious(P < 0.01). Results from this study clearly indicated that KF5 strain was safe and had not adverse reaction.