Isolation Of Probiotic Lactic Acid Bacteria From Meles Meles Feces And Identification Of Genes Associated With Probiotic Functions

Lactic acid bacteria are one kind of important reserviors for mining probiotic strains.Screening probiotic lactic acid bacterial strains with good colonization ability is of great significance for development of animal probiotic products.Animaloriginated probiotic strains usually exhibit excellent colonization ability,and thus show great application advantages in breeding and raising industry.Meles meles is a kind of omnivorous animal,and the intestinal microflora of Meles meles has been demonstrated to be a good resiovior for probiotic strain identification.In this study,246 lactic acid bacterial strains were isolated from 21 Meles meles fecal samples collected from Shanghai and Yangzhou.The taxonomic affiliation of the 246 strains was determined by 16S rDNA sequencing,and 6 genera,including Lactobacillus,Enterococcus,Weissiella,Streptococcus,Streptococcus and Lactococcus,were identified,among which Lactobacillus was most predominant genera,accounting for～59.75%of the total 246 strains.Geographic specific distribution patterns of certain taxa were observed when investigated at species level,for example,strains affiliated with L.animalis and L.salivarius were only identified from meles samples collected in Shanghai but not from samples collected in Yangzhou,while strains affiliated with L.pentosus were only identified from samples collected in Yangzhou.Furthermore,the strains isolated in Shanghai showed higher diversity compared with those isolated in Yangzhou.These differences may be related to the living environment and diet differences between the Meles meles living in the two regions.The antagonistic activities of these abtained strains against three representative pathogens,including Salmonella Derby,S.Typhimurium and S.Enteritis,were further determined.The results suggested that the antagonistic activity varied among the 246 strains,while certain strains,such as L.salivarius S32,exhibited strong antagonistic activity against all the three pathogens,indicative of application potential of these strains with high antagonistic activity.L.salivarius is an important resource for probiotics development.In this study,nine representative L.salivarius strains were selected,and the antagonistic activities against pathogens,acid and bile salt tolerance ability,auto-aggregation ability,as well as the ability to co-aggregate with pathogens and prevent pathogenic bacteria adhere onto host cells,were determined.The results demonstrated that the probiotic properties varied much among the nine L.salivarius strains,however,certain strains including S3 2 could tolerate against strong acid and bile salt stresses,and showed high antagonistic activity.Moreover,S32 could reduce the population of the pathogenic bacteria via co-aggregation and prevent the pathogenic bacteria adhere onto the host cells.These results suggested S32 was a good candidate to develop probiotic products.The genome sequences of the nine L.salivarius strains were determined,and the genes that might be associated with the probiotic features were identified through comparative genomics analysis,aiming to reveal the molecular mechanisms related to the probiotic properties of L.salivarius and contribute to efficient probiotic strains screening practices.Overall,we isolated multiple latic acid bacterial strains from the fecal samples of Meles meles,and identified a strain,L.salivarius S32,with good probiotic properties.The genomic features that were associated with probiotic properties of L.salivarius were further explored.These results laid a foundation for probiotic strain screening,probiotic product development and application practices.