Browsing by Subject "HUMAN GUT MICROBIOTA"

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  • Kostopoulos, Ioannis; Aalvink, Steven; Kovatcheva-Datchary, Petia; Nijsse, Bart; Backhed, Fredrik; Knol, Jan; de Vos, Willem M.; Belzer, Clara (2021)
    The human gastrointestinal tract is colonized by a diverse microbial community, which plays a crucial role in human health. In the gut, a protective mucus layer that consists of glycan structures separates the bacteria from the host epithelial cells. These host-derived glycans are utilized by bacteria that have adapted to this specific compound in the gastrointestinal tract. Our study investigated the close interaction between two distinct gut microbiota members known to use mucus glycans, the generalist Bacteroides thetaiotaomicron and the specialist Akkermansia muciniphila in vitro and in vivo. The in vitro study, in which mucin was the only nutrient source, indicated that B. thetaiotaomicron significantly upregulated genes coding for Glycoside Hydrolases (GHs) and mucin degradation activity when cultured in the presence of A. muciniphila. Furthermore, B. thetaiotaomicron significantly upregulated the expression of a gene encoding for membrane attack complex/perforin (MACPF) domain in co-culture. The transcriptome analysis also indicated that A. muciniphila was less affected by the environmental changes and was able to sustain its abundance in the presence of B. thetaiotaomicron while increasing the expression of LPS core biosynthesis activity encoding genes (O-antigen ligase, Lipid A and Glycosyl transferases) as well as ABC transporters. Using germ-free mice colonized with B. thetaiotaomicron and/or A. muciniphila, we observed a more general glycan degrading profile in B. thetaiotaomicron while the expression profile of A. muciniphila was not significantly affected when colonizing together, indicating that two different nutritional niches were established in mice gut. Thus, our results indicate that a mucin degrading generalist adapts to its changing environment, depending on available carbohydrates while a mucin degrading specialist adapts by coping with competing microorganism through upregulation of defense related genes.
  • Derrien, Muriel; Belzer, Clara; de Vos, Willem M. (2017)
    Akkermansia muciniphila is an intestinal bacterium that was isolated a decade ago from a human fecal sample. Its specialization in mucin degradation makes it a key organism at the mucosal interface between the lumen and host cells. Although it was isolated quite recently, it has rapidly raised significant interest as A. muciniphila is the only cultivated intestinal representative of the Verrucomicrobia, one of the few phyla in the human gut that can be easily detected in phylogenetic and metagenome analyses. There has also been a growing interest in A. muciniphila, due to its association with health in animals and humans. Notably, reduced levels of A. muciniphila have been observed in patients with inflammatory bowel diseases (mainly ulcerative colitis) and metabolic disorders, which suggests it may have potential anti-inflammatory properties. The aims of this review are to summarize the existing data on the intestinal distribution of A. muciniphila in health and disease, to provide insight into its ecology and its role in founding microbial networks at the mucosal interface, as well as to discuss recent research on its role in regulating host functions that are disturbed in various diseases, with a specific focus on metabolic disorders in both animals and humans. (C) 2016 Elsevier Ltd. All rights reserved.
  • Bui, Thi Phuong Nam; Troise, Antonio Dario; Nijsse, Bart; Roviello, Giovanni N; Fogliano, Vincenzo; de Vos, Willem M. (2020)
    Our study aim is to investigate the role of Intestinimonas, Nε-fructosyllysine (FL)-degrading bacterium, in infants and adults. We used lysine and subsequently FL in anaerobic serial dilutions of stools of infants and adults to enrich lysine and FL-degrading species. The fecal microbiota of adults were able to ferment lysine and FL to butyrate. Different groups of Intestinimonas spp. were detected from all lysine enrichments whereas the FL enrichments consisted of broader taxonomic groups with a reduced abundance of Intestinimonas-related species. Remarkably, the capability to degrade FL was only observed in formula-fed but not in breast-fed infants, which may relate to high contents of FL in formulas after thermal treatment. This possibility was supported by analyzing metagenomic datasets of 3-month and 4-month infants. Our data indicate the key role of Intestinimonas-like bacteria in FL degradation in formula-fed infants and adults as a profound example of adaptation of intestinal bacteria to dietary components.
  • Brodmann, Theodor; Endo, Akihito; Gueimonde, Miguel; Vinderola, Gabriel; Kneifel, Wolfgang; de Vos, Willem M.; Salminen, Seppo; Gomez-Gallego, Carlos (2017)
    Novel microbes are either newly isolated genera and species from natural sources or bacterial strains derived from existing bacteria. Novel microbes are gaining increasing attention for the general aims to preserve and modify foods and to modulate gut microbiota. The use of novel microbes to improve health outcomes is of particular interest because growing evidence points to the importance of gut microbiota in human health. As well, some recently isolated microorganisms have promise for use as probiotics, although in-depth assessment of their safety is necessary. Recent examples of microorganisms calling for more detailed evaluation include Bacteroides xylanisolvens, Akkermansia muciniphila, fructophilic lactic acid bacteria (FLAB), and Faecalibacterium prausnitzii. This paper discusses each candidate's safety evaluation for novel food or novel food ingredient approval according to European Union (EU) regulations. The factors evaluated include their beneficial properties, antibiotic resistance profiling, history of safe use (if available), publication of the genomic sequence, toxicological studies in agreement with novel food regulations, and the qualified presumptions of safety. Sufficient evidences have made possible to support and authorize the use of heat-inactivated B. xylanisolvens in the European Union. In the case of A. muciniphila, the discussion focuses on earlier safety studies and the strain's suitability. FLAB are also subjected to standard safety assessments, which, along with their proximity to lactic acid bacteria generally considered to be safe, may lead to novel food authorization in the future. Further research with F. prausnitzii will increase knowledge about its safety and probiotic properties and may lead to its future use as novel food. Upcoming changes in EUU Regulation 2015/2283 on novel food will facilitate the authorization of future novel products and might increase the presence of novel microbes in the food market.
  • Rajilic-Stojanovic, Mirjana; de Vos, Willem M. (2014)