Effect Of Epilactose On Probiotic Efficacy Of Bifidobacterium And Its Mechanism

Epilactose is a rare disaccharide which is linked by D-galactose and D-mannose through ?-1,4 glycoside bond,it is isomer with lactose and lactulose.Epilactose can promote the proliferation of Bifidobacterium and Lactobacillus in rat intestine,showing good probiotics potential.Bifidobacterium is the earliest colonized and dominant probiotic bacteria in the gastrointestinal tract of healthy infants.It has many beneficial activities such as inhibiting intestinal pathogens and regulating the structure of intestinal flora.Clostridium perfringens,as a common pathogen in the intestinal tract of livestock and poultry breeding animals,can cause intestinal diseases and food safety problems,so it is urgent to control them effectively.In this paper,epilactose,a rare disaccharide,was used in the research fields of Bifidobacterium proliferation and Clostridium perfringens biological control.The purpose of this study was to explore the probiotic effect and mechanism of epilactose on Bifidobacterium,to further develop the probiotic potential of epilactose,and to maintain intestinal health and control intestinal diseases.In this paper,epilactose was prepared by enzymatic conversion of lactose.Based on the original preparation process in our laboratory,according to the solubility characteristics of epilactose and lactose,unreacted lactose was precipitated and removed from the reaction system,which greatly simplified the steps of preparing high-purity epilactose in the laboratory,and provided sufficient samples for subsequent research.Eight kinds of Bifidobacterium were cultured in medium with epilactose and its isomer lactose or lactulose as carbon source,and their proliferation was evaluated.Bifidobacterium longum and Clostridium perfringens were co-cultured in the medium with epilactose,lactose or lactulose as carbon source.The growth status of the two bacteria was determined by colony counting.The antimicrobial activity of the supernatant of the culture of Bifidobacterium longum against nine pathogenic bacteria in the medium of epilactose,lactose and lactulose was determined by Oxford cup method,for discussing the combined bacteriostatic effect of epilactose and Bifidobacterium longum.The transcriptome data of Bifidobacterium breve in epilactose,galactose and mannose medium were also analyzed to elucidate the metabolic pathway and probiotic mechanism of epilactose in Bifidobacterium breve.The results showed that epilactose with purity(?98%)was obtained as a follow-up experimental material by using the optimized preparation process of epilactose.The culture results of 8 kinds of Bifidobacteria showed that 4 strains of Bifidobacterium longum,Bifidobacterium infantis,Bifidobacterium breve and Bifidobacterium adolescentisa from human intestinal tract could effectively proliferate with epilactose.The growth of Clostridium perfringens was obviously inhibited by Bifidobacterium longum in the co-culture system with epilactose and its isomers as carbon source,and epilactose played a significant role in improving the survival rate of Bifidobacterium longum.Oxford cup method showed that the bacteriostatic effect was related to the bacteriostatic substances in the culture supernatant of Bifidobacterium longum.The results of transcriptome analysis of Bifidobacterium breve showed that Bifidobacterium breve expressed three isoenzymes that hydrolyzed ?-1,4 glycoside bonds and four transporters that were mainly involved in the translocation of epilactose.It was presumed that epilactose could be hydrolyzed into galactose and mannose components to provide energy for the bacterium after entering the bacterium through the transport system.In addition,epilactose also promotes the biosynthesis of lactic acid,purine nucleotides,amino acids,folic acid and peptidoglycan of Bifidobacterium breve,and the transmembrane transport of metabolites.This paper not only evaluates the probiotic effect of epilactose on Bifidobacterium proliferation and pathogenic bacteria inhibition,but also reveals the inherent mechanism of the probiotic effect of epilactose from the perspective of gene expression in the metabolic pathway of Bifidobacterium.