Preparation of microbial oligosaccharide with prebiotic function

The invention provides a method for preparing microbial oligosaccharide with probiotic action. The method is characterized in that: a sugar producing culture medium is used for liquid fermentation of K.rhinoscleromatis K13 to extract extracellular polysaccharide; enzymatic solution of phage glycanase is prepared, the enzymatic solution and water solution of extracellular polysaccharide are mixed for enzymolysis, the undegraded macro molecular sugar is removed by ultrafiltration, and the obtained filtrate is refined and condensed to obtain the microbial oligosaccharide KOS. Tests show that themicrobial oligosaccharide KOS is non-digestible oligosaccharide which can promote the growth of probiotics such as bifidobacterium, lactobacillus and the like, inhibit the growth of harmful bacteria such as pathogenic bacteria, putrefying bacteria and the like, and has the functions of improving the micro ecological environment of the intestinal tract and cleaning the intestinal tract. The microbial oligosaccharide KOS is novel probiotics, which is novel microbial oligosaccharide which is obtained by degrading the extracellular polysaccharide of the K.rhinoscleromatis K13 through the phage glycanase, and the raw materials used in the method are different from those of other polysaccharides, and the result repeatability is good due to the degradation by an enzyme method, so that the application prospect is wide.