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Early life microbiota encompasses of a large percentage of Bifidobacterium, while it is not sufficiently understood how the Bifidobacterium population develops after infant’s birth. Current study investigated the longitudinal changes in Bifidobacterium population during the first two years of life in 196 term born infants (1,654 samples) using 16S rRNA-23S rRNA internal transcribed spacer (ITS) sequence analysis. Throughout the first two years of life, Bifidobacterium breve, Bifidobacterium longum subsp. longum and Bifidobacterium adolescentis were most dominant and prevalent in the Bifidobacterium population, while B. breve had the highest relative abundance and prevalence during the first week of life and it was taken over by B. longum subsp. longum around two years after birth. Sampling time points, early antibiotic(s) exposure (effect only measurable within a month after birth), delivery mode (effect still detectable two-months after birth) and feeding mode (effect lasted until six months after birth), significantly contributed to the overall variation in the bifidobacterial population. From six months onwards, introducing of solid food and cessation of breastfeeding were accompanied with drastic changes in the composition in bifidobacterial population. Altogether, current study confirmed the effect of potential contributors to the longitudinal changes within the bifidobacterial population during the first two years of life.

01 december 2023, Item does not contain fulltext, The impact of carbohydrate quality, measured by the carbohydrate quality index (CQI), on gut microbiota and health has been scarcely investigated. The aim of this study was to cross-sectionally and longitudinally explore the relationships between CQI, fecal microbiota, and cardiometabolic risk factors in an elderly Mediterranean population at high cardiovascular risk. At baseline and 1-year, CQI was assessed from food frequency questionnaires data, cardiometabolic risk factors were measured, and fecal microbiota profiled from 16S sequencing. Multivariable-adjusted linear regression models were fitted to assess the associations between tertiles of baseline CQI, fecal microbiota, and cardiometabolic risk factors at baseline, and between tertiles of 1-year change in CQI, 1-year change in fecal microbiota and cardiometabolic risk factors. Cross-sectionally, higher CQI was positively associated with Shannon alpha diversity index, and abundance of genera Faecalibacterium and Christensenellaceae R7 group, and negatively associated with the abundance of Odoribacter, and uncultured Rhodospirillales genera. Some of these genera were associated with higher glycated hemoglobin and lower body mass index. In addition, we observed a positive association between CQI, and some pathways related with the metabolism of butyrate precursors and plants-origin molecules. Longitudinally, 1-year improvement in CQI was associated with a concurrent increase in the abundance of genera Butyrivibrio. Increased abundance of this genera was associated with 1-year improvement in insulin status. These observations suggest that a better quality of carbohydrate intake is associated with improved metabolic health, and this improvement could be modulated by greater alpha diversity and abundance of specific genera linked to beneficial metabolic outcomes.

Contains fulltext : 298915.pdf (Publisher’s version ) (Open Access), Early life is a sensitive period when microbiota-gut-brain interactions may have important impact on development. This study investigated the associations of the gut microbiota in the first three years of life (two, six, and 12 weeks, and one and three years) with problem behavior and executive functions in N = 64 three-year-old children. Higher relative abundance of Streptococcus at the age of two weeks, as well as its trajectory over time (including ages two, six and 12 weeks, and one and three years), was related to worse executive functions. Higher relative abundance of [Ruminococcus] torques group at the age of three years, as well as its trajectory from one to three years, was associated with less internalizing behavior. Besides, several robust age-specific associations were identified: higher Bifidobacterium relative abundance (age three years) was associated with more internalizing and externalizing issues; higher Blautia relative abundance (age three years) was linked to less internalizing behavior; and increased relative abundance of an unidentified Enterobacteriaceae genus (age two weeks) was related to more externalizing behavior. Our findings provide important longitudinal evidence that early-life gut microbiota may be linked to behavioral and cognitive development in low-risk children., 23 november 2023, 17 p.

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Beneficial effects of Bifidobacterium spp. on gut microbiota development and infant health have been reported earlier. Therefore, supplementation of infant formulas with probiotic bifidobacteria, as well as prebiotics stimulating bifidobacterial growth, has been proposed. Here, we studied the faecal microbiome of infants supplemented with specialized nutrition, of which some received a standard amino acid-based formula (AAF) and others an AAF with a specific mixture of prebiotics and a probiotic (synbiotics) using metaproteomics and 16S rRNA gene sequencing. Faecal samples were taken at baseline, as well as after 6 and 12 months fed with the specialized formula. The aim was to compare microbial differences between infants treated with the standard AAF and those who received the additional synbiotics. Our findings show that infants who received AAF with synbiotics have significantly higher levels of Bifidobacteriaceae DNA as well as significantly increased levels of Coriobacteriaceae proteins, over time. Moreover, at visit 12 months higher levels of some bifidobacterial carbohydrate-active enzymes, known to metabolize oligosaccharides, were observed in the synbiotic group compared to the non-synbiotic group. The results indicate that the synbiotics provided in our study are trackable in faecal samples on the DNA and protein level during the intervention period.

The impact of carbohydrate quality, measured by the carbohydrate quality index (CQI), on gut microbiota and health has been scarcely investigated. The aim of this study was to cross-sectionally and longitudinally explore the relationships between CQI, fecal microbiota, and cardiometabolic risk factors in an elderly Mediterranean population at high cardiovascular risk. At baseline and 1-year, CQI was assessed from food frequency questionnaires data, cardiometabolic risk factors were measured, and fecal microbiota profiled from 16S sequencing. Multivariable-adjusted linear regression models were fitted to assess the associations between tertiles of baseline CQI, fecal microbiota, and cardiometabolic risk factors at baseline, and between tertiles of 1-year change in CQI, 1-year change in fecal microbiota and cardiometabolic risk factors. Cross-sectionally, higher CQI was positively associated with Shannon alpha diversity index, and abundance of genera Faecalibacterium and Christensenellaceae R7 group, and negatively associated with the abundance of Odoribacter, and uncultured Rhodospirillales genera. Some of these genera were associated with higher glycated hemoglobin and lower body mass index. In addition, we observed a positive association between CQI, and some pathways related with the metabolism of butyrate precursors and plants-origin molecules. Longitudinally, 1-year improvement in CQI was associated with a concurrent increase in the abundance of genera Butyrivibrio. Increased abundance of this genera was associated with 1-year improvement in insulin status. These observations suggest that a better quality of carbohydrate intake is associated with improved metabolic health, and this improvement could be modulated by greater alpha diversity and abundance of specific g

Preterm birth interrupts the natural, intrauterine growth path of infants that occurs during the third trimester. As a result of preterm birth, there is a discrepancy between the maturation status of the gastrointestinal tract and the process of microbial colonization in early life. Yet, the concordant maturation of the gastrointestinal tract and the microbiome is pivotal for growth and health of the preterm infant. Neonatal support in the early life of preterm infants offers the opportunity to orchestrate the maturation of the immature gastrointestinal tract and the colonizing microbes. Despite continuous improvements in preterm infant care, optimal feeding is challenging due to the infant’s immaturity.The intestinal bacteria and fungi are pivotal in health and disease. In preterm infants, variation in the gut microbiota (in this thesis the bacterial community) and mycobiota (the fungal community of the microbiota) is introduced due to a unique set of environmental conditions. Within this thesis, we hypothesized that prematurity of the gut microbiota may be an inconspicuous challenge in nutritional neonatal care. Moreover, we expected the intestinal fungi to be affected by clinical variables in early life. A better understanding of the development of the gastrointestinal tract and the microbes in preterm infants is key for optimal nutritional support. The work in this thesis therefore studied the maturation of the gastrointestinal tract and of the intestinal microbes in preterm infants with their implications for infant growth, development and health.The infants studied in this thesis participated previously in a single-center, observational study in which they were admitted to the neonatal intensive care unit or the pediatric ward of the Isala Women and Children’s Hospital (Zwolle, The Netherlands). The preterm and full-term infants were born between 24 and 42 weeks of gestation and were followed in the first six postnatal weeks, during which clinical variables an

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Contains fulltext : 234211.pdf (Publisher’s version ) (Open Access)

The research in this thesis aims to understand the mechanism used by Akkermansia muciniphila to survive and thrive in the complex and competitive ecosystems of the human gut. We evaluated the ability of A. muciniphila to utilize and degrade HMOs and mucin glycans as a carbohydrate specialist and the advantage of this phenotype in this highly competitive environment. As it has been demonstrated, A. muciniphila can have an important role in human (metabolic) health and it is essential to understand the functions and resilience of A. muciniphila in such communities. This can further expand our knowledge on the benefits that A. muciniphila can bring for human health, but potentially also help to design (nutritional) therapies to support A. muciniphila’s activity in the gut to even further support human health.In Chapter 1, a brief overview of the human intestinal microbiota is provided, focusing on the host-derived glycans that affect the physiology and composition of the gut microbiota. Furthermore, A. muciniphila, a resident of the mucosal layer in the gut, is introduced. The capacity of A. muciniphila to use glycoside hydrolases (GHs) to degrade glycosidic linkages found in mucin and human milk oligosaccharides (HMOs) constituted the motivation for the research described in this thesis.Chapter 2 provides an overview on the presence and functionality of A. muciniphila in different parts of the gastrointestinal tract. Akkermansia muciniphila has been found in human milk, the oral cavity, the pancreas, the biliary system, the small intestine, and the appendix. Hypothetical functions of A. muciniphila in these different niches are proposed, highlighting also that further research is needed to fully understand the versatile roles that A. muciniphila may have in the digestive tract.In Chapter 3 we hypothesized that the presence of A. muciniphila in infant’s intestine is the result of its ability to use its glycan degrading enzymes to break down HMOs. After growth of A. muc

The establishment of the gut microbiota immediately after birth is a dynamic process that may impact lifelong health. At this important developmental stage in early life, human milk oligosaccharides (HMOs) serve as specific substrates to shape the gut microbiota of the nursling. The well-orchestrated transition is important as an aberrant microbial composition and bacterial-derived metabolites are associated with colicky symptoms and atopic diseases in infants. Here, we study the trophic interactions between an HMO-degrader, Bifidobacterium infantis and the butyrogenic Anaerostipes caccae using carbohydrate substrates that are relevant in the early life period including lactose and total human milk carbohydrates. Mono-and co-cultures of these bacterial species were grown at pH 6.5 in anaerobic bioreactors supplemented with lactose or total human milk carbohydrates. A. caccae was not able to grow on these substrates except when grown in co-culture with B. infantis, leading to growth and concomitant butyrate production. Two levels of cross-feeding were observed, in which A. caccae utilised the liberated monosaccharides as well as lactate and acetate produced by B. infantis. This microbial cross-feeding points towards the key ecological role of bifidobacteria in providing substrates for other important species that will colonise the infant gut. The progressive shift of the gut microbiota composition that contributes to the gradual production of butyrate could be important for host-microbial crosstalk and gut maturation.

Contains fulltext : 225516.pdf (Publisher’s version ) (Open Access), SCOPE: Akkermansia muciniphila (A. muciniphila) is an intestinal commensal with anti-inflammatory properties both in the intestine and other organs. The aim is to investigate the effects of oral administration of A. muciniphila on lipid metabolism, immunity, and cuff-induced neointima formation in hyperlipidemic APOE*3-Leiden (E3L).CETP mice. METHODS AND RESULTS: Hyperlipidemic male E3L.CETP mice are daily treated with 2 × 10(8) CFU A. muciniphila by oral gavage for 4 weeks and the effects are determined on plasma lipid levels, immune parameters, and cuff-induced neointima formation and composition. A. muciniphila administration lowers body weight and plasma total cholesterol and triglycerides levels. A. muciniphila influences the immune cell composition in mesenteric lymph nodes, as evident from an increased total B cell population, while reducing the total T cell and neutrophil populations. Importantly, A. muciniphila reduces the expression of the activation markers MHCII on dendritic cells and CD86 on B cells. A. muciniphila also increases whole blood ex vivo lipopolysaccharide-stimulated IL-10 release. Finally, although treatment with A. muciniphila improves lipid metabolism and immunity, it does not affect neointima formation or composition. CONCLUSIONS: Four weeks of treatment with A. muciniphila exerts lipid-lowering and immunomodulatory effects, which are insufficient to inhibit neointima formation in hyperlipidemic E3L.CETP mice.

Contains fulltext : 218284.pdf (publisher's version ) (Open Access), Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder. Given the growing evidence of gut microbiota being involved in psychiatric (including neurodevelopmental) disorders, we aimed to identify differences in gut microbiota composition between participants with ADHD and controls and to investigate the role of the microbiota in inattention and hyperactivity/impulsivity. Fecal samples were collected from 107 participants (NADHD = 42; Ncontrols = 50; NsubthreholdADHD = 15; range age: 13-29 years). The relative quantification of bacterial taxa was done using 16S ribosomal RNA gene amplicon sequencing. Beta-diversity revealed significant differences in bacterial composition between participants with ADHD and healthy controls, which was also significant for inattention, but showing a trend in case of hyperactivity/impulsivity only. Ten genera showed nominal differences (p < 0.05) between both groups, of which seven genera were tested for their association with ADHD symptom scores (adjusting for age, sex, body mass index, time delay between feces collection and symptoms assessment, medication use, and family relatedness). Our results show that variation of a genus from the Ruminococcaceae family (Ruminococcaceae_UCG_004) is associated (after multiple testing correction) with inattention symptoms and support the potential role of gut microbiota in ADHD pathophysiology.

Contains fulltext : 217761.pdf (publisher's version ) (Open Access)

Contains fulltext : 224857pub.pdf (publisher's version ) (Open Access), Several bacteria in the human gut microbiome have been associated with colorectal cancer (CRC) by high-throughput screens. In some cases, molecular mechanisms have been elucidated that drive tumorigenesis, including bacterial membrane proteins or secreted molecules that interact with the human cancer cells. For most gut bacteria, however, it remains unknown if they enhance or inhibit cancer cell growth. Here, we screened bacteria-free supernatants (secretomes) and inactivated cells of over 150 cultured bacterial strains for their effects on cell growth. We observed family-level and strain-level effects that often differed between bacterial cells and secretomes, suggesting that different molecular mechanisms are at play. Secretomes of Bacteroidaceae, Enterobacteriaceae, and Erysipelotrichaceae bacteria enhanced cell growth, while most Fusobacteriaceae cells and secretomes inhibited growth, contrasting prior findings. In some bacteria, the presence of specific functional genes was associated with cell growth rates, including the virulence genes TcdA, TcdB in Clostridiales and FadA in Fusobacteriaceae, which both inhibited growth. Bacteroidaceae cells that enhanced growth were enriched for genes of the cobalamin synthesis pathway, while Fusobacteriaceae cells that inhibit growth were enriched for genes of the ethanolamine utilization pathway. Together, our results reveal how different gut bacteria have wide-ranging effects on cell growth, contribute a better understanding of the effects of the gut microbiome on host cells, and provide a valuable resource for identifying candidate target genes for potential microbiome-based diagnostics and treatment strategies.

The development of the gut microbiome from birth through to childhood is thought to be important for establishing a healthy symbiosis, but much is yet to be learnt about this phase of microbiome development. Perturbations of gut microbiome during this development have been associated with the pathology of diseases, such as allergy. In Chapter 2, we describe this dynamic period of gut microbiome development, the various factors involved in shaping its composition and the importance for the concurrent maturation of the immune system. Environmental factors including birth mode, exposure to antibiotics and household exposures (such as siblings and furry pets) represent important factors impacting its development, and which also have been epidemiologically implicated in the risk to develop allergic disease. Several paediatric studies indeed associated altered gut microbiota with development of allergic disease. Breastfeeding represents the most significant factor in shaping early life microbiome and is associated with several short-term and long-term health benefits, including a lower risk of developing allergic disease. Specific prebiotic or synbiotic (when combined with probiotics) ingredients added to infant formula may exert similar effects on gut microbiota composition and activity, which may benefit infants for whom breastfeeding is not possible. Bifidobacteria are the most abundant bacteria in breastfed infants, but often under-represented in 16S rRNA surveys of diversity, due to poor DNA extraction techniques, poor PCR primer choice or a combination of both. In Chapter 3, we optimized a commonly used “universal” PCR primer set and demonstrated the effective recovery of this genus without compromising the detection of other genera. In Chapter 4 we applied the optimized pyrosequencing method described in Chapter 3 to analyse the gut microbiota of infants at high-risk of developing allergy, who participated in a clinical trial that investigated the effects of a part

Biologists and clinicians all try to find correlations between the gut microbiome and the health outcomes. Most often, these studies do not show a causal link. The main challenge is to figure out if changes in the gut microbiome actually play a role in a disease.

There are many associations described between states of disease and the composition of your microbiota. But what does an association between the microbiota and disease mean? How can this information help us to better understand disease, development? Can this information help us to develop strategies for prevention, prediction and treatment of disease?

Contains fulltext : 196433.pdf (publisher's version ) (Open Access), BACKGROUND: The effects of gut microbiota on human traits are expected to be small to moderate and adding the complexity of the human diseases, microbiome research demands big sample sizes. Fecal samples for such studies are mostly self-collected by participants at home. This imposes an extra level of complexity as sample collection and storage can be challenging. Effective, low-burden collection and storage methods allowing fecal samples to be transported properly and ensuring optimal quality and quantity of bacterial DNA for upstream analyses are necessary. Moreover, accurate assessment of the microbiome composition also depends on bacterial DNA extraction method. The aim of this study was to evaluate the reliability and efficiency of the OMNIgene*GUT kit as a participant-fecal friendly collection method (storage at room temperature for 24 h (O24h) or 7 days (O7d)) in comparison to the standard collection method (Fresh, storage at 4 degrees C for less than 24 h) in terms of amount of variability and information content accounting for two common DNA extraction methods. RESULTS: Fourteen fecal samples were collected from healthy individuals (7 males, 7 females). Collection and storage methods did not differ significantly in terms of DNA concentration and Shannon diversity index. Phylum relative abundance showed significant differences for Bacteroidetes, Actinobacteria and Cyanobacteria. The differences were observed between control (Fresh) and O24h methods, but not between Fresh and O7d. These differences were not seen when performing bacterial DNA quantification based on three bacterial groups: Bacteroides spp., Bifidobacterium spp. and Clostridium cluster IV, which represent three major phyla: Bacteroidetes, Actinobacteria and Firmicutes respectively. The two DNA extraction methods differ in terms of DNA quantity, quality, bacterial diversity and bacterial relative abundance. Furthermore, principal component analysis revealed differences in microbial structure, wh

Functioning of the gastrointestinal tract, and of the microbiota residing therein, is of significance for nutrient digestion and absorption, pathogen resistance and optimal immune performance. During early life, development of the gut microbiota coincides, and affects, development of the metabolic, cognitive and immune system. Proper establishment of the gut microbiota is therefore considered essential for healthy development. In early life, the intestinal microbiota is relatively unstable and responsive to perturbations. Factors that are recognised to influence neonatal microbiota development include gestational age, delivery mode, nutrition and antibiotic use. As such, gut microbiota establishment is likely to be impacted in preterm infants, since they have an immature gut and are commonly exposed to caesarean section delivery, specific feeding regimens and antibiotic treatment. Although gut microbiota development can be negatively impacted during early life, the developing microbiota also provides an opportunity to be targeted as means of therapeutic strategy to support healthy growth and development. In light of this, it is important to understand how the preterm infant gastrointestinal tract is functioning, which microbes colonise, what the microbes are doing and how microbiota establishment is affected. In this thesis, gastrointestinal function and microbiota development during the early life of preterm infants, and the impact of various host and environmental factors on this development, were studied. The research described in this thesis was performed using material obtained during a single-centre, observational study including infants admitted to the neonatal unit born between 24-42 weeks gestation. A total of 238 infants (119 <32 weeks gestation, 119 >32 weeks gestation) were followed during the first six postnatal weeks, during which clinical factors were documented, and faeces and gastric aspirates were longitudinally collected for microbiota analysis. M

The gut harbors a complex ecosystem in which many bacteria, both beneficial and pathogens, thrive. The potential importance of A. muciniphila as a member of the intestinal microbiota comes from the fact that A. muciniphila is reversely correlated with several diseases and reduce the fat mass gain of mice fed a high fat diet. We describe the use of genome-scale metabolic models to further understand the genetic and metabolic potential of microbiota members, as well as potential phenotypes and influence on the host. We emphasize the importance of culturing bacteria and provide an outline in which GEMs are used to aid in the development of minimal culture media. The use of GEMs for the development of minimal media was applied for A. muciniphila. We found that the essential components of A. muciniphila medium are L-threonine and either N-acetylglucosamine (GlcNAc) or N-acetylgalactosamine (GalNAc). The composition of the minimal medium was used to develop an animal component free medium. The addition of soy derived peptides increased the growth rate an yield, and the omission of animal components makes the cultured bacteria applicable in humans. We o analyzed the expression of the gene Amuc_1100, which was found to be involved in host signaling previously. There was no significant alteration in the expression of this genes, or genes in the associated gene cluster. In a subsequent experiment, we discovered that the anaerobic bacterium A. muciniphila is able to tolerate ambient . The addition of oxygen during growth increased the growth rate and yield, which was the result of cytochrome bd mediated oxygen reduction. To protect A. muciniphila during gastric passage, we encapsulated the cell in a water in oil in water double emulsion. We found a 100 fold higher survival of the encapsulated cells. We concluded that the double emulsion could be an effective matrix for the viable delivery of A. muciniphila. The final steps required for the application of A. muciniphila as ther

The co-evolution of the human host and the gut microbiota has led to bacterial adaption to forage on host-produced glycans such as human milk oligosaccharides (HMOS) and mucins. In early life, the HMOS that are present in mother milk contribute to the establishment of a healthy gut microbiota. Furthermore, mucins that cover the intestinal lining create a stable niche for bacterial colonization throughout a person’s life. Due to the highly complex nature of these host-secreted glycans, bacteria equipped with specific glycan-degrading enzymes can exploit them as substrate for growth. Subsequently, the glycan-degrading bacteria can drive microbial networks via cross-feeding. The glycan-foraging microbial population exerts a large influence on the host physiology, by influencing the immune, metabolic, and neurological development early in life, and by conferring colonisation resistance throughout life. The work described in this thesis aims to improve our understanding of the metabolic dependencies between the milk- and mucin-degrading microbes (Akkermansia muciniphila, Bifidobacterium spp. and Bacteroides spp.) and butyrate-producing bacteria (Anaerostipes caccae, Eubacterium hallii, and Faecalibacterium prausnitzii). Bacteria-derived butyrate is the preferred energy source for host epithelial cells and is associated with a range of beneficial effects including enhancement of colonic barrier function, increased satiety, and protection against inflammation, and cancer. In the introductory chapter, the role of human milk and mucin glycans in fostering the gut microbial network is discussed. As such, the molecular mechanisms of glycan-foraging by key microbial species and the potential butyrate-inducing interaction among gut symbionts is presented. In Chapter 2 and 3, the role of HMOS as selective substrates for microbial growth that drive the establishment of the infant gut microbiota was investigated. At this developmental stage, HMOS promote the dominance of bifidobact

A dysbiosis in the intestinal microbiome plays a role in the pathogenesis of several immunological diseases. These diseases often show a gender bias, suggesting gender differences in immune responses and in the intestinal microbiome. We hypothesized that gender differences in immune responses are associated with gender differences in microbiota. We demonstrated mouse strain dependent gender differences in the intestinal microbiome. Interestingly, a cluster of colonic genes (related to humoral and cell-mediated immune responses) correlated oppositely with microbiota species abundant in B6 females and in BALB/c males. This suggests that with different genetic backgrounds, gender associated immune responses are differentially regulated by microbiota. The net result was the same, since both mouse strains showed similar gender induced differences in immune cell populations in the mesenteric lymph nodes. Therefore, host-microbe interactions might be more complicated than assumed, as bacterial-species adaptations might be highly dependent on the genetic make-up of the individual.

A dysbiosis in the intestinal microbiome plays a role in the pathogenesis of several immunological diseases. These diseases often show a gender bias, suggesting gender differences in immune responses and in the intestinal microbiome. We hypothesized that gender differences in immune responses are associated with gender differences in microbiota. We demonstrated mouse strain dependent gender differences in the intestinal microbiome. Interestingly, a cluster of colonic genes (related to humoral and cell-mediated immune responses) correlated oppositely with microbiota species abundant in B6 females and in BALB/c males. This suggests that with different genetic backgrounds, gender associated immune responses are differentially regulated by microbiota. The net result was the same, since both mouse strains showed similar gender induced differences in immune cell populations in the mesenteric lymph nodes. Therefore, host-microbe interactions might be more complicated than assumed, as bacterial-species adaptations might be highly dependent on the genetic make-up of the individual.

Host glycans are paramount in regulating the symbiotic relationship between humans and their gut bacteria. The constant flux of host-secreted mucin at the mucosal layer creates a steady niche space for bacteria colonization. Mucin, characterized by complex molecular structure, exerts selective nutritional pressure for mucin-degrading bacteria. Mucin degradation by keystone species subsequently drives the local trophic chain and shapes mucosal microbial assembly a.k.a. mucobiome. This study investigates mucin-driven trophic interaction between the specialized mucin-degrader, Akkermansia muciniphila and butyrogenic gut commensals. Co-cultures of A. muciniphila with non-mucolytic butyrogens (Anaerostipes caccae and Eubacterium hallii) were grown in minimal media supplemented with pure mucin. Metabolites (HPLC) and meta-transcriptome (RNA-seq) were studied. Mucin degradation by A. muciniphila produced mucin-derived monosaccharides and metabolites (galactose, fucose, mannose, GlcNAc and acetate) for the growth of butyrogens (A. caccae and E. hallii) resulted in 2mM butyrate production. Interestingly, co-culture of A. muciniphila with E. hallii demonstrated mutual relationship, in which pseudovitamin B12 production by E. hallii facilitated propionate production by A. muciniphila. Cobalamin-dependent methylmalonyl-CoA mutase genes (Amuc_1983 and Amuc_1984) were upregulated in A. muciniphila monoculture, indicated the attempt by A. muciniphila to activate propionate production pathway by synthesizing more key catalytic enzymes. Differential analysis (DESeq2) showed the presence of butyrogens resulted in an altered transcriptional profile of A. muciniphila. E. hallii in particular, incurred high functional impact on A. muciniphila gene expression. Mucosal subpopulation driven by A. muciniphila could result in butyrate and propionate production. Deciphering the underlying mechanism of this microbial tropism is crucial for the understanding of mucosal health and pathophysiolog, Host glycans are paramount in regulating the symbiotic relationship between humans and their gut bacteria. The constant flux of host-secreted mucin at the mucosal layer creates a steady niche space for bacteria colonization. Mucin, characterized by complex molecular structure, exerts selective nutritional pressure for mucin-degrading bacteria. Mucin degradation by keystone species subsequently drives the local trophic chain and shapes mucosal microbial assembly a.k.a. mucobiome. This study investigates mucin-driven trophic interaction between the specialized mucin-degrader, Akkermansia muciniphila and butyrogenic gut commensals. Co-cultures of A. muciniphila with non-mucolytic butyrogens (Anaerostipes caccae and Eubacterium hallii) were grown in minimal media supplemented with pure mucin. Metabolites (HPLC) and meta-transcriptome (RNA-seq) were studied. Mucin degradation by A. muciniphila produced mucin-derived monosaccharides and metabolites (galactose, fucose, mannose, GlcNAc and acetate) for the growth of butyrogens (A. caccae and E. hallii) resulted in 2mM butyrate production. Interestingly, co-culture of A. muciniphila with E. hallii demonstrated mutual relationship, in which pseudovitamin B12 production by E. hallii facilitated propionate production by A. muciniphila. Cobalamin-dependent methylmalonyl-CoA mutase genes (Amuc_1983 and Amuc_1984) were upregulated in A. muciniphila monoculture, indicated the attempt by A. muciniphila to activate propionate production pathway by synthesizing more key catalytic enzymes. Differential analysis (DESeq2) showed the presence of butyrogens resulted in an altered transcriptional profile of A. muciniphila. E. hallii in particular, incurred high functional impact on A. muciniphila gene expression. Mucosal subpopulation driven by A. muciniphila could result in butyrate and propionate production. Deciphering the underlying mechanism of this microbial tropism is crucial for the understanding of mucosal health and pathophysiolog

Your body is not only made up of human cells, but also by trillions of bacteria, fungi and viruses. Together they make up the human microbiome and have a tremendous impact on your health. For example, what you eat and drink impacts the microbiome. In this course, you will learn how the human microbiome plays an important role in maintaining normal gut function, digesting certain nutrients, early life development, behavior and, disorders like irritable bowel syndrome (IBS), obesity and diabetes. You will learn how to distinguish fact from fiction about the role of the microbiome in health and disease.

Gut barrier function is key in maintaining a balanced response between the host and its microbiome. The microbiota can modulate changes in gut barrier as well as metabolic and inflammatory responses. This highly complex system involves numerous microbiota-derived factors. The gut symbiont Akkermansia muciniphila is positively correlated with a lean phenotype, reduced body weight gain, amelioration of metabolic responses and restoration of gut barrier function by modulation of mucus layer thickness. However, the molecular mechanisms behind its metabolic and immunological regulatory properties are unexplored. Herein, we identify a highly abundant outer membrane pili-like protein of A. muciniphila MucT that is directly involved in immune regulation and enhancement of trans-epithelial resistance. The purified Amuc_1100 protein and enrichments containing all its associated proteins induced production of specific cytokines through activation of Toll-like receptor (TLR) 2 and TLR4. This mainly leads to high levels of IL-10 similar to those induced by the other beneficial immune suppressive microorganisms such as Faecalibacterium prausnitzii A2-165 and Lactobacillus plantarum WCFS1. Together these results indicate that outer membrane protein composition and particularly the newly identified highly abundant pili-like protein Amuc_1100 of A. muciniphila are involved in host immunological homeostasis at the gut mucosa, and improvement of gut barrier function.

Transcriptome analysis comparing the gene expression of A. muciniphila grown on mucin or glucose media confirmed the activity of the genes involved in mucin degradation, and revealed most of them to be upregulated in the presence of mucin. A. muciniphila grown on glucose showed a stress response and upregulation of specific genes, such as Amuc_1094 which was identified as a glucokinase induced by glucose. The transcriptional response was confirmed by a proteome analysis, reinforcing the adaptation of A. muciniphila to the mucosal environment. These new findings provide molecular insights into the lifestyle of A. muciniphila, and further confirm its role as a mucin specialist in the gut., Transcriptome analysis comparing the gene expression of A. muciniphila grown on mucin or glucose media confirmed the activity of the genes involved in mucin degradation, and revealed most of them to be upregulated in the presence of mucin. A. muciniphila grown on glucose showed a stress response and upregulation of specific genes, such as Amuc_1094 which was identified as a glucokinase induced by glucose. The transcriptional response was confirmed by a proteome analysis, reinforcing the adaptation of A. muciniphila to the mucosal environment. These new findings provide molecular insights into the lifestyle of A. muciniphila, and further confirm its role as a mucin specialist in the gut.