Screening And Identification Of The Cholesterol-Lowering Probiotics And Blood Lipid Reduction

With the rapid development of social economy and the improved living standard,the average life expectancy of people have been prolonged,the aging population has become increasingly prominent.Due to the decline of basal metabolism and physiological functions in the elderly,the incidence of coronary heart disease and other diseases has increased rapidly.High cholesterol is one of the largest risk factors for coronary heart disease.The development of high cholesterol-lowering probiotic products is of great significance for reducing the incidence of coronary heart disease.As a folk fermentation product,traditional ferment drinks not only have nutritional value,but also have a significant effect on losing weight.The high cholesterol-lowering Strains were isolated from traditional ferment drinks,analyze the effects of prebiotics on the probiotic characteristics of the strains and compound the strains.Finally,to study the safety of compound probiotics and the inhibition effect of high fat diet-induced obesity in mice.This study isolated 51 strains from ferment drinks,among which S-8,M-7 and M-16 have been screened by the tolerance of bile salt,acid resistance,hydrophobicity,self-agglomera ability,bile salt hydrolytic enzyme activity and cholesterol lowering properties,and the cholesterol reduction rates of which were 25.43%,37.06%and 47.41%,respectively.The tolerance of bile salt tolerance were 42.09%,65.64%,22.80%;S-8 strain had the highest hydrophobicity in xylene,and the hydrophobicity was up to 35.91%,and the hydrophobicity of M-7 in chloroform was 45.22%.Both strains have good acid resistance and self-agglomera,after standing for 24 hours,the self-agglomera ability was more than 80%.The hpocholesterolemic effect was investigated.It was found that the activity of intracellular enzymes were stronger than that of extracellular ones.Through the morphological observation and 16S rDNA molecular analysis,the S-8 strain was identified as L.paracasei strain,the other two strain were identified as Staphylococcus hominis strain.This research investigated the effects of inulin,lactulose,galactooligosaccharides,stachyose,and glucose on the probiotic characteristics of four strains.The acid resistance,bile salt tolerance,hydrophobicity of the strains and lactic acid content were determined.The results showed that L.paracasei S0940 and S.thermophilus ldbm had significantly higher lactic acid in medium added lactulose than other prebiotics,the concentration of lactic acid were 11.27 g/L and 10.83 g/L,respectively.S.thermophilus gldl has higher acid resistance and bile salt tolerance in the medium with galactooligosaccharides,and the rate of acid resistance rate was 86.17%,the bile salt tolerance rate was 58.09%.The hydrophobicity ofS.thermophilus gld2 in lactulose was significantly higher than that of stachyose,indicating that the probiotic characteristics of the strains are dependent on prebiotics.This study provides a theoretical basis for further researching the best prebiotic-probiotic combination.The safety of the strains were evaluated through the Nitroreductase test,Hemolysis test,and Antibiotic sensitivity test.And the body weight,Lee's index,viscera index,serum index and fece-related indexes were studied for the hypolipidemic function of compound probiotics.The results showed that mouse weight,serum TC,TG,LDL-C significantly decreased,HDL-C was increased significantly(P<0.05),and showed a dose-dependent.Compared with the high-fat model group,the fecal water content and triglyceride content of the probiotics group were significantly increased,and The number of beneficial bacteria in feces increased and the number of pathogenic bacteria decreased significantly,indicating that the compound probiotics had certain regulatory function on intestinal flora.In order to further explore the effect of probiotics on liver oxidative damage in high-fat diet mice,liver triglyceride content,related lipid-lowering enzyme activity,and malondialdehyde content were measured.The results showed that probiotics can reduce liver TG and glutathione Enzyme and catalase activities increased,reducing MDA activity,showing strong antioxidant activity.