13 Diet-microbe interactions play a crucial role in infant development and modulation of the early-life 14 microbiota. The genus Bifidobacterium dominates the breast-fed infant gut, with strains of B. 15 longum subsp. longum (B. longum) and B. longum subsp. infantis (B. infantis) particularly prevalent. 16Although transition from milk to a more diversified diet later in infancy initiates a shift to a more 17 complex microbiome, specific strains of B. longum may persist in individual hosts for prolonged 18 periods of time. Here, we sought to investigate the adaptation of B. longum to the changing infant 19 diet. Genomic characterisation of 75 strains isolated from nine either exclusively breast-or formula-20 fed (pre-weaning) infants in their first 18 months revealed subspecies-and strain-specific intra-21 individual genomic diversity with respect to glycosyl hydrolase families and enzymes, which 22 2 persistence in a single host and may contribute to rational development of new dietary therapies for 31 this important developmental window. 32 33 35 particularly the ones involved in the degradation of breast milk-associated human milk 52 oligosaccharides (HMOs) (8). The presence of these genes is often species-and indeed strain-53 specific, and has been described in B. breve, B. bifidum, B. longum, B. infantis, and more rarely in B. 54 pseudocatenulatum (8,(25)(26)(27). However, previous studies have indicated co-existence of 55Bifidobacterium species and strains in individual hosts, resulting in interaction and metabolic co-56 operation within a single (HMO-associated) ecosystem (1, 28). 57Transition from breastfeeding to a more diversified diet and the introduction of solid foods has been 58 considered to initiate the development of a functionally more complex adult-like microbiome with 59 genes responsible for degradation of plant-derived complex carbohydrates, starches, and 60 xenobiotics, as well as production of vitamins (29, 30). Non-digestible complex carbohydrates such 61 as inulin-type fructans (ITF), arabino-xylans (AX) or arabinoxylo-oligosaccharides (AXOS) in 62 3 complementary foods have been proposed to potentially exert beneficial health effects through 63 their bifidogenic and prebiotic properties and resulting modulation of the intestinal microbiota and 64 metabolic end-products (31)(32)(33)(34). 65Despite the shift in microbiota composition during weaning, specific strains of Bifidobacterium, and 66 B. longum in particular, have previously been shown to persist in individuals over time (35, 36). B. 67 longum is currently recognised as four subspecies: longum and infantis (characteristic of the human 68 gut microbiota), and suis and suillum (from animal hosts) (37, 38). It is considered the most common 69 and prevalent species found in the human gut, with B. longum subsp. infantis detected in infants, 70 and B. longum subsp. longum widely distributed in both infants and adults (39, 40). The differences 71 in prevalence between the two subspecies, and the ability of infant, adult and elderly host t...
The diets of industrialized countries reflect the increasing use of processed foods, often with the introduction of novel food additives. Xanthan gum is a complex polysaccharide with unique rheological properties that have established its use as a widespread stabilizer and thickening agent1. However, little is known about its direct interaction with the gut microbiota, which plays a central role in digestion of other, chemically-distinct dietary fiber polysaccharides. Here, we show that the ability to digest xanthan gum is surprisingly common in industrialized human gut microbiomes and appears to be contingent on the activity of a single bacterium that is a member of an uncultured bacterial genus in the family Ruminococcaceae. We used a combination of enrichment culture, multi-omics, and recombinant enzyme studies to identify and characterize a complete pathway in this uncultured bacterium for the degradation of xanthan gum. Our data reveal that this keystone degrader cleaves the xanthan gum backbone with a novel glycoside hydrolase family 5 (GH5) enzyme before processing the released oligosaccharides using additional enzymes. Surprisingly, some individuals harbor a Bacteroides species that is capable of consuming oligosaccharide products generated by the keystone Ruminococcaceae or a purified form of the GH5 enzyme. This Bacteroides symbiont is equipped with its own distinct enzymatic pathway to cross-feed on xanthan gum breakdown products, which still harbor the native linkage complexity in xanthan gum, but it cannot directly degrade the high molecular weight polymer. Thus, the introduction of a common food additive into the human diet in the past 50 years has promoted the establishment of a food chain involving at least two members of different phyla of gut bacteria.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with đź’™ for researchers
Part of the Research Solutions Family.