Abstract
Bifidobacteria are among the first colonizers of the human gastrointestinal tract. Different bacterial species use different mechanisms for utilization of various carbon sources in order to establish themselves in the complex microbial ecosystem of the gut. However, these mechanisms still need to be explored. Here, a large gene–phenotype correlation analysis was carried out to explore the metabolic and genetic diversity of bifidobacterial carbohydrate utilization abilities. In this study, we used 21 different carbohydrates to determine the growth phenotypes, the distribution of glycoside hydrolases (GHs), and gene clusters related to the utilization of multiple carbon sources in six human-residential Bifidobacterium species. Five carbohydrates significantly stimulated growth of almost all strains, while the remaining sugars exhibited species- and strain-specificity. Correspondingly, different Bifidobacterium species also had specific GHs involved in fermentation of plant or host glycans. Moreover, we analyzed several carbohydrate utilization gene clusters, such as 2-fucosyllactose (2′FL), sialic acid (SA), and fructooligosaccharide (FOS). In summary, by using 217 bifidobacterial strains and a wide range of growth substrates, our research revealed inter- and intra-species differences in bifidobacterial in terms of carbohydrate utilization. The findings of this study are useful for the process of developing prebiotics for optimum growth of probiotics, especially Bifidobacterium species.
Highlights
Much experimental data has shown significant differences in the abundance and composition of bifidobacteria in the intestines of people of different ages [1]
All B. adolescentis and B. pseudocatenulatum strains, nearly half of B. longum and only two of B. breve were able to grow on XOS
Except for the GOS/lactulose degradation gene clusters (Figure S1), we found that 17 strains of B. breve and 19 strains of B. longum encode β-1,4-galactanase of GH53, which is predicted to participate in the degradation of type I AG (Table S3)
Summary
Much experimental data has shown significant differences in the abundance and composition of bifidobacteria in the intestines of people of different ages [1]. Bifidobacterial species are vertically transmitted via the mother [3]. Bifidobacterial species abundance decreases, and accounts for approximately 4.4% of the adult intestinal flora and exhibits a declining trend with age [4]. From their composition, bifidobacteria can be loosely divided into two types according to different age groups of people, “infant-type” and “adult-type”. Infant-type bifidobacteria mainly include Bifidobacterium bifidum, Bifidobacterium longum subsp. Infantis, Bifidobacterium breve, and Bifidobacterium longum subsp.
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