Screening And Evaluation Of Probiotic Lactobacillus Strains With Function For Regulating Intestinal Motility

The problem of intestine health have been affecting people's lives.Dietary intervention is considered to be an effective way to maintain intestinal health.Probiotics,as a dietary ingredient,have a wide range of probiotic properties,especially on intestinal regulation.In recent years,researches have been carried out on probiotics with intestine-regulating function.However,there are still not many probiotic Lactobacillus in China.In this paper,45 Lactobacillus strains were screened from samples of fermented food and people feceas.Lactobacilli with potential of intestine-regulating was screened according to physiological characteristics,and then investigated in a mouse model.The main contents were as follows:The physiological characteristics of 45 lactobacilli were measured,analyzed and evaluated by the acid and bile salt tolerance test,the short chain fatty acid test and oligosaccharide test.Among these strains,Lactobacillus casei LC9,Lactobacillus plantarum LP17,Lactobacillus brevis LB25,Lactobacillus fermentum LF37,L.fermentum LF38 and Lactobacillus rhamnus LR45 show high survival rate in acid and bile salt tolerance test.Lactobacillus gasseri LG1,L.plantarum LP21,L.fermentum LF37 and L.rhamnus LR45 show the outstanding ability to produce short chain fatty acids,especially acetic acid.Thirty of tested strains can fermentated all the three oligosaccharides(fructo-oligosaccharide,xylo-oligosaccharides and galacto-oligosaccharide).Based on the physiological characteristics listed above,15 strains were selected for further study.According to ISO 10932-2010,the minimum inhibitory concentration of 12 common antibiotics applicable to lactobacilli were measured,and the range of safe strains is determined.Except L.fermentum LF34,the other 14 lactobacilli all meet the safety.Based on the results of physiological characteristics,3 strains of Lactobacillus,L.casei LC9,L.fermentum LF37 and L.rhamnus LR45 were considered to have the potential of intestinal-regulating.After 15 days of gavage,the regulation of the 3 Lactobacillus strains on normal mice intestinal tract was evaluated.By measuring the health indices(body weight,food intake and drinking water volume)of mice,these 3 strains were proved to have no adverse effects on mice health.The effects of these lactobacilli on the digestive function of mice were evaluated by calculating and analyzing the utilization rate of food.Results showed the 3 strains had no negative effects on the normal digestion of mice.The effect of lactobacilli on intestinal motility of mice was evaluated by measuring small intestine propulsive rates,first black stool time,water content of mice feces,content of the short chain fatty acids of mice feces and content of the gastrointestinal regulation peptide in the serum.Results showed the 3 strains could significantly increase small intestine propulsive rates of mice,shorten the first black stool time,regulate the gastrointestinal regulation peptide in the serum,and accelerate the intestinal motility.By analyzing the composition and structure of fecal flora of mice,the 3 lactobacilli were found to increase the relative abundance of beneficial bacteria in fecal flora of mice,and to improve the structure of fecal flora.Based on the results above,we found that L.casei LC9,L.fermentum LF37 and L.rhamnus LR45 have functions for regulating intestinal motility.These three strains can be used as new probiotic strain resources.