Study On The Utilization Of 2'-fucosyllactose By Bifidobacterium And Its Effect On Intestinal Microecology Of Mice

2'-Fucosyllactose(2'FL)is the most abundant breast milk oligosaccharide in breast milk,which can selectively promote the proliferation of bifidobacteria.At present,research on the use of 2'FL by bifidobacteria focuses on the key enzyme genes and utilization mechanisms by a single strain,but lacks the genus rules for the use of 2'FL by bifidobacteria and the influence of bifidobacteria that can use 2'FL on healthy hosts.Therefore,this article aims to evaluate and compare the ability of different bifidobacteria to utilize 2'FL based on the correlation analysis between phenotype and genotype.On this basis,further exploration of the effects of bifidobacteria with different utilization of 2'FL on the intestinal microecology of mice and to provide theoretical guidance for the development of personalized prebiotics for different bifidobacteria.The main findings are as follows:To evaluate the ability of different bifidobacteria to utilize 2'FL,genotype analysis was performed on 151 bifidobacteria.The genotype prediction results show that only 37 strains with the ability to use 2'FL,including 22 B.bifidum,2 B.breve,2 B.longum subsp.longum,9 B.longum subsp.infantis,whilst B.adolescentis,B.animalis,B.pseudocatenulatum,and B.angulatum could not use 2'FL.And on this basis,using 2'FL as the sole carbon source,the 151 strains' ability to utilize 2'FL was determined.The results showed that only 37 strains can utilize 2'FL,and most of the strains are newborns and infant source.The comparison of genotype and phenotype showed that the phenotypic result was completely consistent with the genotype prediction,and there were also strain differences in the use of 2'FL.In order to further investigate the competitive utilization of 2'FL by bifidobacteria,five different species of bifidobacteria that can use 2'FL were mixed cultured.The results showed that when 2'FL was used as the sole carbon source for mixed culture,the growth of B.dentium FJSWXJ29M2 occupies a competitive advantage.In order to study the effect of bifidobacteria with different utilization capacity of 2'FL on the intestinal microecology of mice,a comparative study was carried out on the feeding mode of bifidobacteria and bifidobacteria combined with 2'FL.The results showed that the five kinds of bifidobacteria had no significant effects on the physiological indicators,intestinal tissue morphology,cytokines,secreted immunoglobulin A,gastrointestinal peptide levels and short-chain fatty acid content in mice,but B.bifidum M130R01M51,B.breve FHuNCS6M1,B.longum subsp.longum CCFM752 and B.longum subsp.infantis SDZC2M4 significantly reduced the species richness of the intestinal flora.In terms of intestinal flora,B.longum subsp.longum CCFM752 and B.longum subsp.infantis SDZC2M4 significantly increased the abundance of Faecalibaculum and Bifidobacterium,respectively.The results of Bifidobacterium combined with 2'FL also showed no significant effect on the physiological indicators,intestinal tissue morphology and secreted immunoglobulin A of mice.In terms of different strains,the combination of B.longum subsp.longum CCFM752 and 2'FL can significantly increase the levels of pro-inflammatory and anti-inflammatory factors;the combination of B.bifidum M130R01M51 and 2'FL can significantly increase the content of excitatory transmission,thereby promoting gastrointestinal peristalsis.Besides,this group also can significantly increase the content of acetic acid and propionic acid,but the combination of B.longum subsp.infantis SDZC2M4 and 2'FL can regulate the level of propionic acid most significantly;The species richness of the intestinal flora is significantly increased when the B.breve FHuNCS6M1 and the B.longum subsp.longum CCFM752 are compounded with 2'FL;At the genus level,the combination of Bifidobacterium and 2'FL,both can increase the abundance of Akkermania.Among them,B.dentium FJSWXJ29M2 is compounded with 2'FL,and the abundance of Akkermania is more significant.In order to simulate the situation where a variety of bifidobacteria in the intestines of infants compete with each other for carbon sources,we further explored the effects of bifidobacteria with different 2'FL utilization capabilities on mice gut microbiota under the competitive pressure of 2'FL as carbon source.The effects of mixed bifidobacteria and mixed bifidobacteria combined with 2'FL were used for comparative research.The results show that mixed bifidobacteria can significantly reduce the content of IL-1? and increase the abundance of bifidobacteria,but it has no significant effect on other indicators.The results of mixed bifidobacteria combined with 2'FL showed that it had no significant effect on physiological indicators,intestinal tissue morphology and secretory immunoglobulin A content in mice.This group can significantly reduce the content of IL-1? and the a diversity index.In addition,it can increase the content of the excitatory transmitter motilin and the abundance of Akkermansia,and significantly increase the level of short-chain fatty acids in the host's intestinal tract.It is worth noting that the B.longum subsp.infantis has higher abundance in a competitive environment.This result is different from the result of in vitro mixed culture of Bifidobacterium with 2'FL as the sole carbon source,which may be related to the adaptability of the host.