[Acid and bile tolerance and cholesterol reduction ability of Lactobacillus paraplantarum].

We studied the acid and bile tolerance of Lactobacillus paraplantarum II 32, and examined the possible mechanisms of cholesterol reduction.Strain II 32 was incubated in MRS (de Man, Rogosa, Sharpe) broth supplemented with cholesterol, and the cholesterol in medium was determined using gas chromatography. We examined cholesterol reducing ability under different conditions, and the relation between growth and cholesterol reduction of strain II 32.Strain II 32 showed acid resistance, bile salt tolerance and the cholesterol-reducing ability. The results indicated that strain II 32 survived at pH2 after 2 h culture and the living bacterial number could reach 10(4) cfu/mL. In addition, the growth of strain II 32 was delayed less than 0.5 h in MRS broth with 0.3% - 0.4% bile salt, when the absorbance value both increased to 0.6 unit. Cholesterol removed by dead and resting cells were 5.64 and 5.90 mg/g of dry weight compared with growing cells, which was 16.98 mg/g of dry weight. Cholesterol removal was greatly associated with growth of the bacteria. The possible mechanisms for removal of cholesterol from media were proposed: assimilation of cholesterol during growth, and binding of cholesterol to the cell surface.Strain II 32 may be promising candidates for use as a dietary adjunct to lower serum cholesterol in vivo.