Screening Of Lactic Acid Bacteria With Probiotic Potential And Function Exploration From Fermented Cornus Officinalis Fruits

Cornus officinalis,originated from Korea and China,is a species of dogwood.It is known as a kind of medicinal plant and nutraceutical.Its fruits have many pharmacological activities,such as hypoglycemic,hypolipidemic and cholesterol-lowing effect,liver and kidney function improvement and antioxidant effect enhancement.C.officinalis is rich in endophytes.Its pharmacological activity may be associated with the metabolic activity of endophytic bacteria.Moreover,the fruits come from a natural reserve should be an excellent resource,because the low impact of antimicrobial contamination may cause non or low intensity of antibiotic activity of their endophytic bacteria,which can be used to improve the stability of C.officinalis or other plant-derived fermented foods and improve their functionality.1.In current study,a total of 189 isolates from fermentation broth of C.officinalis fruits were identified as LAB.According to the growth rates under unfavorable conditions of low pH and high concentration of bile salts,11 isolates were selected.There were 10 Lactobacillus plantarum and 1 Lactobacillus casei,which were identified by API 50 CHL as well as 16 s rDNA gene sequence.2.The probiotic potential of 11 isolates was then evaluated by in vitro tests according to the criterion of FAO/WHO,including antagonistic action,aggregation,adhesion capacity and antibiotic susceptibility.The results of principal component analysis(PCA)based on probiotic characteristics suggested that the scores of 11 isolates were higher than Lactobacillus rhamnosus GG(LGG)and L.plantarum 3701,3735,25234,2519,3725 and 3730 were promising probiotic candidates.Furthermore,the antibiotic susceptibility profiles of 11 isolates were similar with LGG,which shows that these isolates are non or low intensity of antibiotic activity.3.C.officinalis has the pharmacological functions of lowering blood lipid and reducing serum cholesterol,which may be related to the functional characteristics of probiotics.Therefore,the ability of cholesterol-lowing of 11 strains in vitro and correlation between bile salt hydrolase(BSH)and cholesterol-lowing as well as between exopolysaccharide(EPS)and cholesterol-lowing were explored.The results of in vitro cholesterol reduction activity of the isolates showed that L.plantarum 3725,3730,3735,25294 and 2519 removed high levels of cholesterol,with values from 37.76% to 47.83%.Relativity analysis showed that the reduction of cholesterol by probiotic bacteria was through co-precipitation with unconjugated bile acids and adsorption of EPS also contributed to the cholesterol-lowering effect of the strains.4.The results of in vitro probiotic characteristics and functional analysis of strains showed that L.plantarum 3725,3730,3735 and 2519 can be further developed into probiotics or plant foods fermentative bacteria.