| Bifidobacterium is one of the primary probiotics in human intestinal tract,which has important physiological significance on human health.Ln recent years,EPS produced by bifidobacterium has attracted much attention because of its potential applications in food biotechnology,cosmetics,pharmaceuticals and other fields.Bifidobacteria-produced EPSs are a kind of carbohydrate polymers which synthesized and presented on the surface of Bifidobacterium.EPS not only benefit health but also have effects on probiotics in the microbial ecosystem.At present,there are few reports on the production of extracellular polysaccharides by Bifidobacterium.Based on the current situation,this study was established on the EPS produced by B.longum ATCC(?) 51870TM,and further studying aimed at the effect of EPS on human gut microbiota in vitro,which provided direction for the development of new probiotics.In this article,through the intestinal microbiota fermentation in vitro,we studied the impact of bifidobacteria-produced exopolysaccharides on human gut microbiota in vitro,which was related to health.Firstly,it carried on the preliminary analysis about the structure of EPS and secondly,we studied the degradation process of EPS and the effect of EPS on human gut microbiota in vitro.Finally,we studied interactions between EPS and anthropogenic probiotics.The research of this paper is mainly divided into the following aspects:1、The structure of EPS was determined preliminarily by Dionex ICS 5000 high purity capillary ion chromatography and infrared chromatography.The results of Dionex ICS 5000 high-purity capillary ion chromatography system showed that EPS had absorption peaks of fucose,rhamnose,galactose/acetyl glucosamine,glucose,and ribose,and the molecular proportion of these monosaccharides was approximately 2:2:440:3:53,which indicated that EPS was rich in monosaccharides,and the monosaccharides of EPS were more complex than previously reported.The infrared spectra of 400～4000 cm-1 showed that EPS was a pyranoid sugar with a-configuration.2、The interaction between EPS and human gut microbiota in vitro was studied by TLC、16SrDNA high-throughput sequencing and gas chromatography.The results showed that human gut microbiota had the capacity to degrade EPS,although the degradation rate was approximately 50%after fermenting for 48 h.EPS can adjust human’s gut microbiota:Collinsella,Coprococcus3,Parabacteroides and Rhodopseudomonas was obviously higher in EPS group;Brevibacillus,Coprococcusl,Dorea,Lachnospira and Porticoccus were significantly higher in EPS group.EPS promoted the growth of Coprococcus.In the fermentation samples,EPS can promote the growth of Bifidobacteria and Lactobacillus.And the fermented samples in EPS group could get together based on the bacterial community,which had good separation from other groups,indicating that the EPS and starch had different regulatory effects on human fecal microbiota.EPS increased the yield of propionic acid,which had statistical significance(P<0.05).3、The interaction between EPS and original Lactobacillus、Bifidobacterium of human.In single bacterium culture experiment,the source of two B.longum in EPS as carbon source of bifidobacterium medium grew well and the degradation rate of EPS can reach 50%after 24 hours,which were higher than Lactobacillus.On the degradation of EPS,the reducing sugar content in all groups with the extension of time,all had a significantly lower trend shows that the experiment of Lactobacillus and Bifidobacterium can degrade the EPS,Bifidobacterium was better than Lactobacillus with use of the EPS.To sum up,EPS could regulate intestinal flora in vitro,and it had good promoting effect on the growth of human original Lactobacillus and Bifidobacterium in this experiment,also probiotics could be well used to degrade the EPS.Therefore,the EPS had a prospect as a new type of prebiotics,and it may play an important role in regulating human gut microbiota and further studies on its functional mechanism are needed in the future. |
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