| 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 diseases in that people suffering from primary hypercholesterolemia. Because of the associated risk of heart disease, there has been an upsurge in finding ways to lower plasma cholesterol levels in such people. Several studies have indicated that consumption of certain lactic acid bacteria and its cultured dairy products resulted in reduction of serum cholesterol levels, and some Lactobacillus spp. can also reduce cholesterol from medium during growth in vitro.ZangLingGu (ZLG), a Tibet traditional yoghurt-like dairy fermented by natural formed ZLG grains, has been handed down to us from ancient times. A variety of potential beneficial effects about ZLG have already been described, such as improvement of host resistance by immunomodulation, depress of serum cholesterol levels and reduction of tumor formation. However, these are not systematic studies on hypocholesterolaemic effects of ZLG grains and its fermented milk. This paper research on the cholesterol-reducing ability and mechanisms of strains isolated from ZLG grains. The main results include:1. Determined cholesterol-reducing ability of ZLG grains, and found it could reduce 13.3% cholesterol from egg yolk. Tamed it with high-cholesterol skim milk supplemented with egg yolk and improved its cholesterol-reducing ability . The cholesterol removed form medium after 24h incubation with ZLG grains varied from 3.24mg/mL to 2.81mg/mL when it was been tamed to 40 generations.2. 11 Lactobacillus spp. strains, 4 Lactococcus spp.strains and 4 yeast strains were isolated from tamed ZLG grains. Cholesterol-reducing ability of those strains differed significantly and most Lactobacillus spp. could reduce cholesterol from medium. Two strains, FML-16, FMLA-1 were selected for next research, which could reduce 51.8%, 47.5% cholesterol form egg yolk . And Bifidobacterium longum BL-1192 was selected at the same time for its ability reducing 60.8% cholesterol from medium.3. According to their morphological and physiological characters, FML-16, FMLA-1 were identified as Lactobacillus casei. Identification results of these two isolates bybacteria auto-analytical system showed the same conclusion.4. The health effects of FML-16, FMLA-1, BL-1192 on serum cholesterol levels were demonstrated in vivo by hyperlipemial mice. Feeding mice with high-cholesterol food supplemented with bile salt, fat, etc, we succeeded in inducing hyperlipemial mice model. Compared with normal mice, the total serum cholesterol (TC) concentration, triglyceride (TG) concentration of those increased significantly after 10 days running ,but high density cholesterol (HDL-C) had very little change. At the same time, an increase in the atherogenic index (AI) were observed, and HDL-C/TC value decreased significantly.5. The effects of L.casei FML-16, FMLA-1, B.longum BL-1192 and Lactobacillus sp. FMLA-3 on serum TC, TG , HDL-C concentration were investigated in artificially-induced hyperlipemial mice. The results showed that the mean values of TC, TG concentrations and atherogenic index were decreased significantly when FML-16, FMLA-1, BL1192 strains were administrated to mice after 14 days running , and HDL-C concentration, HDL-C/TC value increased obviously at the same time. However, Lactobacillus sp.FMLA-3, which could not remove cholesterol in vitro had no effects on serum TC , TG and HDL-C levels of hyperlipemial mice.6. Studied on the mechanism of the cholesterol-reducing ability of L.casei FML-16, FMLA-1 , B.longum BL-1192 , includes: analysis of cholesterol assimilation and precipitation; effects of bile salts concentrations on cholesterol-reducing; cells resistance to lysis by ultrasonic when cultured in the presence of bile salts and cholesterol or not. The result proved that those three strains differed significantly in the amount of cholesterol...
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