Screening Of Cholesterol Lowering Lactic Acid Bacteria And Their Cholesterol Lowering Mechanism

Cardiovascular diseases(CVD),as one main inducement of the global mortality,killed about 16.7 million people every year worldwide.Some studies demonstrated that high cholesterol is closely related to CVD,which induced various symptoms of atherosclerosis like coronary heart disease.The risk of vascular diseases like coronary heart disease(CHD)is reduced by 2% accompanied with the decrease by 1% of the content of serum cholesterol.Pharmacological treatment is one of the most important therapies currently,however,limited because only 18% patients achieved their most ideal treatment outcome.Thus,it is necessary to find other therapeutic methods to resolve the issue of high cholesterol.Recent decades,probiotic like lactic acid bacteria(LAB)have drawn increasing public attention due to their outstanding probiotic properties.The capability of lowering lipids and cholesterol level was becoming a research hotspot and has a vast development prospect.In this study,WS1,LP2,LP3,LP4,LP5 and LP6 could reduce cholesterol strongly,thus were screen out from 30 test LAB strains isolated from traditional fermented vegetables to analysis their physiological properties.Technological conditions of reduce cholesterol were optimized using the Design-Expert software for response surface methodology on a basis of single-factor experiment.Meanwhile,the preliminary study of degradation mechanism was carried out.The main conclusions were as follows:(1)The growths and acid-producing abilities of WS1,LP2,LP3 and LP6 were steady when cultivated in MRS broth.This four strains have an outstanding acid-resistant,bile tolerance,as well as higher survival rates under simulated gastric juice conditions.The presence of bile salt could promote cholesterol degradation.The degrading cholesterol capability of seed fermentation broth during log phase was stronger than that of stable phase.(2)The effects of medium compositions and culture conditions on cholesterol degradation were explored using WS1 and LP6 as the test strains.The optimum cholesterol degradation conditions of both strains were obtained.For WS1,the influence of medium compositions,in turn,were X1(glucose)>X3(sulfate)>X2(Twain-80).Culture conditions were C(pH)>B(temperature)>A(time).For LP6,the influence of medium compositions,in turn,were X3(sulfate)> X1(glucose)>X2(Twain-80).Culture conditions were C(p H)>B(temperature)>A(time).(3)A preliminary study of cholesterol-lowering mechanism for WS1 and LP6 was executed based on their physiological characteristics.Data showed that the cholesterol-lowering performance of strains achieved a stable trend after a slight decline,accompanied with the change of time.Different phases of strains possessed different cholesterol-lowering abilities.In addition,the contents of total cholesterol in supernatant and cell pellet of strains decreased,show that the mechanism of assimilation and adsorption by the strains existed,and a small amount of cholesterol is biodegradable,the specific mechanism of the strains will be studied in future.