Specificity of Polysaccharide Use in Intestinal Bacteroides Species Determines Diet-Induced Microbiota Alterations

Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Cell (Impact Factor: 32.24). 06/2010; 141(7):1241-52. DOI: 10.1016/j.cell.2010.05.005
Source: PubMed


The intestinal microbiota impacts many facets of human health and is associated with human diseases. Diet impacts microbiota composition, yet mechanisms that link dietary changes to microbiota alterations remain ill-defined. Here we elucidate the basis of Bacteroides proliferation in response to fructans, a class of fructose-based dietary polysaccharides. Structural and genetic analysis disclosed a fructose-binding, hybrid two-component signaling sensor that controls the fructan utilization locus in Bacteroides thetaiotaomicron. Gene content of this locus differs among Bacteroides species and dictates the specificity and breadth of utilizable fructans. BT1760, an extracellular beta2-6 endo-fructanase, distinguishes B. thetaiotaomicron genetically and functionally, and enables the use of the beta2-6-linked fructan levan. The genetic and functional differences between Bacteroides species are predictive of in vivo competitiveness in the presence of dietary fructans. Gene sequences that distinguish species' metabolic capacity serve as potential biomarkers in microbiomic datasets to enable rational manipulation of the microbiota via diet.

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    • "Therefore, we next tested the potential of levan- 540 coated Co 3 O 4 NPs to dissolve in the growth medium and serve as a Co source for gut bacteria 541 using B. thetaiotaomicron. According to recent data, this bacterium which is abundant in the 542 human gut, can utilize levan as a sole carbon source using an extracellular endolevanase for 543 levan depolymerization (Adamberg et al., 2014; Sonnenburg et al., 2010). It was previously 544 shown that B. thetaiotaomicron, though possessing Co-containing vitamin B 12 -dependent 545 enzymes, is auxotrophic for this vitamin and encodes multiple B 12 transporters to internalize it 546 from environment (Degnan, Barry, Mok, Taga, & Goodman, 2014). "
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    ABSTRACT: Levan, fructose-composed biopolymer of bacterial origin, has potential in biotechnology due to its prebiotic and immunostimulatory properties. In this study levan synthesized by levansucrase from Pseudomonas syringae was thoroughly characterized and used as multifunctional biocompatible coating material for microelement-nanoparticles (NPs) of selenium, iron and cobalt. Transmission electron microscopy (TEM), hydrodynamic size measurements (DLS) and X-ray photoelectron spectroscopy (XPS) showed the interaction of levan with NPs. Levan stabilized the dispersions of NPs, decreased their toxicity and had protective effect on human intestinal cells Caco-2. In addition, levan attached to cobalt NPs remained accessible as a substrate for the colon bacteria Bacteroides thetaiotaomicron. We suggest that the combination of levan and nutritionally important microelements in the form of NPs serves as a first step towards a novel "2 in 1" approach for food supplements to provide safe and efficient delivery of microelements for humans and support beneficial gut microbiota with nutritional oligosaccharides.
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    • "As such, undigested polysaccharides reach the colon and serve as a major energy source for the GM. Not surprisingly, the enzymatic capacity of any singular bacterial taxon is a major determinant of fitness within its environment (Sonnenburg et al. 2010). While this has been elegantly demonstrated on the level of individual species, diet clearly places selective pressures on the GM at higher phylogenetic levels as well. "
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    • "The fructose-based carbohydrates are well-known to influence the intestinal microbiota, and the basis of Bacteroides spp. proliferation in response to fructose-based carbohydrates is known (Sonnenburg et al., 2010). In addition, the fructose-based carbohydrates derived from plants such as Chinese yam and Chinese bitter melon as well as JBO VS have attracted attention as prebiotic foods, and were reported to promote the growth of helpful intestinal microbiota such as Bacteroides spp. "
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