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[Bacterial flora of the conjunctival sac of the horse].

The AA. report the results of taxonomic research conducted on the conjunctival sac of 59 horses for identification of the present bacterial flora. In the controlled animals, it was observed, at the level of the considered niche, a community constituted of normal bacterial populations, but not autochtonous in the significance they attributed from DUBOS et al., relative to the characterization of the indigenous microbiota of the intestine. The isolated normal bacterial flora seems to be constituted of: Micrococcus (subgroup 6 of Baird-Parker, M. luteus, Micrococcus spp.) isolated in 49,15% of the samples; Staphylococcus aureus and St. epidermidis (18,64%); Moraxella osloensis, M. phenylpiruvica, M. equi and Moraxella spp. (11,86%); Bacillus cereus (11,86%); Neisseria catarrhalis (8,47%); Streptococcus equi and Str. zooepidemicus (6,77%); Corynebacterium spp. (6,77%) and Acinetobacter lwoffi (5,08%). The AA. have found, besides, a particular group of bacteria of uncertain classification, attributed to the coryneforms and found in 30,50% of the examined horses. So-called transient bacteria taxa have been considered are Streptomyces spp., isolated in the 10,16% of the controlled subjects, Aerococcus viridans and Bacillus spp. found in only one equine.

Animals↗

PubMed2000

In vitro fermentation pattern of D-tagatose is affected by adaptation of the microbiota from the gastrointestinal tract of pigs.

Knowledge of the fermentation pattern of D-tagatose is important for the assessment of energy value and compliance of D-tagatose. In vitro fermentation experiments with pig intestinal contents and bacteria harvested from the gastrointestinal tract of pigs were used to investigate the degradation of D-tagatose and the formation of fermentation products. Two groups of eight pigs were fed either a control diet containing 150 g/kg sucrose or a diet which had 100 g/kg of the sucrose replaced by D-tagatose. After 18 d the pigs were killed and the gastrointestinal contents collected for in vitro studies. No microbial fermentation of D-tagatose occurred in the stomach or in the small intestine, whereas the sugar was fermented in the cecum and colon. Formate, acetate, propionate, butyrate, valerate, caproate and some heptanoate were produced by the microbial fermentation of D-tagatose by gut microbiota. Hydrogen and methane were also produced. The population of D-tagatose-degrading bacteria in fecal samples and the capacity of bacteria from the hindgut to degrade D-tagatose were higher in the pigs adapted to D-tagatose compared with unadapted pigs. In unadapted pigs, the major fermentation product from D-tagatose was acetic acid. Much more butyric and valeric acids were produced from D-tagatose by bacterial slurries of tagatose-adapted pigs compared with unadapted pigs; this was especially the case for samples from the colon. We conclude that D-tagatose is not fermented in the upper gastrointestinal tract, and the ability of the large intestinal microbiota to ferment D-tagatose is dependent on adaptation.

Acetic Acid↗

PubMed2001

The influence of a colonic microbiota on HPMA copolymer lectin conjugates binding in rodent intestine.

Germ-free (GF) animals lack a colonic microflora like that seen in conventional (CV) animals. Bacterial presence plays a role in the development of glycoproteins in the gastrointestinal (GI) tract; the absence of a microbiota has been seen to suppress the production of certain glycoproteins and glycolipids. Binding patterns of lectins are modified when glycoprotein structures are altered (e.g., during development or disease). Little information on lectin binding patterns in mature GF animals is available. We examined the binding of free and N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-conjugated fluorescein isothiocyanate (FITC)-labeled wheat germ agglutinin (WGA) [P(HPMA)-(WGA-FITC)] and FITC-labeled peanut agglutinin (PNA) [P(HPMA)-(PNA-FITC)] in CV and GF mouse colon with and without neuraminidase pretreatment. Anti-Thomsen-Friedenreich (TF) antigen (a development and disease-related glycoprotein) antibody binding was also examined in these tissues. Subtle differences were seen in the binding patterns between CV and GF animals. CV animals showed strong P(HPMA)-(WGA-FITC) binding in goblet cells, but minimal P(HPMA)-(PNA-FITC) binding was visible. In GF animals, luminal surface binding of P(HPMA)-(WGA-FITC) was visible, and goblet cell binding of P(HPMA)-(PNA-FITC) was seen. These subtle changes suggest that altered glycoprotein expression occurred under GF conditions.

Animals↗

PubMed2026

Gut microbiota-derived metabolites target C5AR1/KDM2A/HCAR3 axis in inflammatory bowel disease: a multi-machine learning algorithms and molecular docking study.

BACKGROUND: Inflammatory bowel disease (IBD) is a chronic recurrent disorder. Gut microbiota-derived metabolites regulate intestinal homeostasis, but their molecular mechanisms in IBD remain unclear. Current studies lack systematic "microbiota-metabolite-target" network mining with multi-method validation. This study integrates network pharmacology, three machine learning algorithms, and molecular docking to construct this regulatory network in IBD. METHODS: Transcriptome data were obtained from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) were identified using limma (p < 0.05, |log2FC| > 0.5). Weighted gene co-expression network analysis (WGCNA) with an optimal soft threshold of β = 7 was performed to identify key module genes. Candidate genes were obtained by intersecting DEGs, gut microbiota-associated genes from the gutMGene database, and WGCNA module genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted to explore the functional roles of candidate genes. Core genes were identified using three machine learning algorithms (LASSO, Boruta, and SVM-RFE), followed by protein-protein interaction (PPI) network analysis. Molecular docking was performed to assess the binding affinities between hub proteins and gut microbiota-derived metabolites. RESULTS: A total of 885 DEGs were identified between the IBD and control groups, including 463 upregulated and 422 downregulated genes. WGCNA identified 280 key module genes from the purple and yellow modules. The intersection of DEGs, gut microbiota-associated genes, and WGCNA module genes yielded 19 core candidate genes. PPI network analysis combined with three machine learning algorithms jointly identified C5AR1, KDM2A, and HCAR3 as core hub genes. ROC curve analysis demonstrated that all three hub genes achieved AUC values greater than 0.7 in both the training and validation sets, indicating excellent diagnostic performance for IBD. Enrichment analysis revealed significant associations with the TNF, NF-κB, and IL-17 signaling pathways. Molecular docking confirmed stable binding of C5AR1 with 1,3-Diphenylpropan-2-Ol (-7.87 ± 0.83 kcal·mol-¹) and HCAR3 with 3-Indolepropionic Acid (-6.35 ± 0.70 kcal·mol-¹), both below -5.0 kcal·mol-¹. CONCLUSION: This study first constructs a "gut microbiota-metabolite-hub gene" axis in IBD, providing a computational framework for microbiota-targeted precision therapy, and identifying C5AR1/KDM2A/HCAR3 as computationally predicted diagnostic biomarkers and 1,3-Diphenylpropan-2-Ol/3-Indolepropionic Acid as candidate intervention molecules that warrant further experimental validation.

Molecular Docking Simulation↗

PubMed2006

Quantification of mucosa-adhered microbiota of lambs and calves by the use of culture methods and fluorescent in situ hybridization coupled with flow cytometry techniques.

The intestinal mucosa-associated microbiota could play important biological roles due to its close proximity with the animal host, but knowledge on its composition is still limited. The aim of this study was to characterize the microbial communities tightly associated with different parts (rumen, duodenum and colon) of the gastrointestinal tract (GIT) of healthy lambs and calves by using both cultural, and fluorescent in situ hybridization-flow cytometry (FCM-FISH) techniques. Lactic acid bacteria genera were one of the predominant bacteria detected in lambs and calves by both methodologies, possibly constituting an index of their healthy status. The levels of Lactobacillus were significantly higher (p<0.05) in the rumen and duodenum of lambs, and in the rumen of calves. The levels of Bifidobacterium were significantly higher (p<0.05) in the colon of both animal species and the rumen of lambs. Significant differences (p<0.05) were found in counts of other microbial groups (yeast, Enterococcus, Propionibacterium, Bacteroides, Clostridium and Enterobacteriaceae) at diverse GI sections depending on the animal species. In general, microbial counts follow the same trends regardless the applied technique. The most remarkable differences were found in detection levels of Bacteroides and Clostridium, which tended to be significantly higher (p<0.05) when analysed by FCM-FISH. This technique also allowed the detection of quantitatively important bacteria (sulphate-reducing bacteria, Atopobium and Coriobacterium), which are difficult to cultivate in selective medium. Therefore, FCM-FISH has been proven to be a sensitive high throughput approach that provides additional information to that obtained by traditional culture techniques about the complexity of the GI ecosystem of these animal species.

Animals↗

PubMed2003

Prebiotics in infant milk formulas: new perspectives.

In recent years it has become accepted that healthy human intestinal microflora may play an important part in priming the infants' systemic and mucosal immunity. Dietary modulation of the gut microbiota is a topical area of nutritional sciences and the main focus of many current functional foods such as non-digestible oligosaccharides (NDOs). Fructo-oligosaccharides (FOS) and trans-beta-galacto-oligosaccharides (TOS) have been claimed to benefit the health of the colon by selectively stimulating the growth of bifidobacteria and lactobacilli (prebiotic effect). It could be of clinical interest to manipulate colonic flora because it is supposed that specific bacteria in the gut microbial microflora could promote potentially antiallergenic processes and play a key part in atopic disease prevention. Supporting this view is the finding that analysis of the composition of the intestinal bacterial populations showed different microbial patterns between healthy and allergic individuals. Assuming that non-digestible TOS and FOS can affect the intestinal ecosystem beneficially, the opportunity for gut flora manipulation arises in bottle-fed infants. New preterm and term infant milk formulas, supplemented with a mixture of TOS and FOS as prebiotic ingredients induced a significantly higher colonization of bifidobacteria and lactobacilli. In the future, selective manipulation of the intestinal microbiota might be an approach to novel prophylactic and therapeutic intervention strategies of atopy, by redirecting allergic Th-2 responses in favour of Th-1 responses.

Bifidobacterium↗

PubMed2026

Probiotic supplementation increases fecal TLR4 agonists without improving disease activity in juvenile idiopathic arthritis: a randomized placebo-controlled trial.

Gut dysbiosis has been implicated in the pathogenesis of juvenile idiopathic arthritis (JIA), suggesting that microbiota-targeted interventions may influence immune signalling during early immune development. We conducted the PERMAJI multicentre randomized, double-blind, placebo-controlled trial to evaluate the effects of probiotic supplementation (VSL#3) on host-microbiota immune interactions and disease activity in children with oligoarticular or RF-negative polyarticular JIA. Participants were randomly assigned (1:1) to receive VSL#3 or placebo for 3 months in addition to standard therapy. Stool and serum samples collected at baseline and month 3 were used to assess gut microbiota composition, fecal innate immune agonists, intestinal permeability, and systemic cytokines. The primary clinical endpoint was the proportion achieving an ACR Pedi 30 response at 3 months. Forty-four children were enrolled between September 2017 and July 2022. Clinical responses did not differ between groups (ACR Pedi 30: 47% with VSL#3 vs 63% with placebo; p = 0.33), and conservative worst-case assumptions for missing data suggested lower response rates with VSL#3 (36% vs 68%; p = 0.03). Probiotic supplementation significantly increased fecal Toll-like receptor 4 (TLR4) agonist activity, whereas gut microbiota diversity, intestinal permeability, and systemic cytokine levels remained unchanged. These findings indicate that probiotic supplementation can modify microbial innate immune signalling without detectable changes in microbial community diversity and may increase exposure to pro-inflammatory microbial stimuli in early-life autoimmune disease. The results highlight the complexity of host-microbiota immune interactions and underscore the need for careful evaluation of microbiome-targeted therapies in paediatric autoimmune disorders.

Humans↗

PubMed2006

Review article: prebiotics in the gastrointestinal tract.

BACKGROUND: Prebiotics are short-chain carbohydrates that alter the composition, or metabolism, of the gut microbiota in a beneficial manner. It is therefore expected that prebiotics will improve health in a way similar to probiotics, whilst at the same time being cheaper, and carrying less risk and being easier to incorporate into the diet than probiotics. AIM: To review published evidence for prebiotic effects on gut function and human health. METHODS: We searched the Science Citation Index with the terms prebiotic, microbiota, gut bacteria, large intestine, mucosa, bowel habit, constipation, diarrhoea, inflammatory bowel disease, Crohn's disease, ulcerative colitis, pouchitis, calcium and cancer, focussing principally on studies in humans and reports in the English language. Search of the Cochrane Library did not identify any clinical study or meta-analysis on this topic. RESULTS: Three prebiotics, oligofructose, galacto-oligosaccharides and lactulose, clearly alter the balance of the large bowel microbiota by increasing bifidobacteria and Lactobacillus numbers. These carbohydrates are fermented and give rise to short-chain fatty acid and intestinal gas; however, effects on bowel habit are relatively small. Randomized-controlled trials of their effect in a clinical context are few, although animal studies show anti-inflammatory effects in inflammatory bowel disease, while calcium absorption is increased. CONCLUSIONS: It is still early days for prebiotics, but they offer the potential to modify the gut microbial balance in such a way as to bring direct health benefits cheaply and safely.

Bone and Bones↗

PubMed1997

The intestines of carnivorous fish: structure and functions and the relations with diet.

The intestine is a complex multifunctional organ. In addition to digesting and absorbing feedstuffs, the intestine is critical for water and electrolyte balance, endocrine regulation of digestion and metabolism, and immunity. The intestines of carnivorous fish have evolved for processing a highly digestible, nutrient dense diet that is high in protein and low in carbohydrate. Correspondingly, abilities to digest protein are well developed, but carbohydrate digestion is low compared to omnivorous and herbivorous fish. Furthermore, the evolutionary stable diet is associated with a lack or reduced abilities to adaptively modulate digestive functions to match changes in diet composition. Despite similar selective pressures, intestinal structure is highly variable among carnivorous fish, reflecting phylogenetic diversity. Due to economic considerations, diets for cultured species often have varying proportions of plant-based ingredients. Although such feeds are effective for raising omnivorous and herbivorous species, they have provided limited success for carnivores, and this has been attributed to digestive limitations. Recent evidence of inflammatory responses to as yet unidentified components of some plants suggest involvement of the enteric immune system. Changes in temperature and salinity alter intestinal structure and functions, and therefore processing of dietary inputs. A relatively unknown component of the intestine involves the resident microbiota and its role in the health and disease of carnivoraus fish.

Adaptation, Biological↗

PubMed2005

Human symbionts use a host-like pathway for surface fucosylation.

The mammalian intestine harbors a beneficial microbiota numbering approximately 10(12) organisms per gram of colonic content. The host tolerates this tremendous bacterial load while maintaining the ability to efficiently respond to pathogenic organisms. In this study, we show that the Bacteroides use a mammalian-like pathway to decorate numerous surface capsular polysaccharides and glycoproteins with l-fucose, an abundant surface molecule of intestinal epithelial cells, resulting in the coordinated expression of this surface molecule by host and symbiont. A Bacteroides mutant deficient in the ability to cover its surface with L-fucose is defective in colonizing the mammalian intestine under competitive conditions.

Adenosine Triphosphate↗

PubMed2026

Multi-omics analysis reveals stage-associated differences in gut immunity and microbiota between juvenile and adult common carp (Cyprinus carpio).

In vertebrates, the development of intestinal immunity is closely associated with dynamic changes in the gut microbiota. However, stage-associated differences in intestinal immunity and gut microbial communities remain poorly characterized in teleost fish. In this study, transcriptomic analysis combined with 16S rRNA gene sequencing was employed to characterize intestinal immunity and gut microbial communities in juvenile and adult common carp (Cyprinus carpio). Transcriptomic profiling revealed marked developmental differences in intestinal immune function. Juvenile carp exhibited a predominantly innate immune phenotype, characterized by elevated expression of pro-inflammatory cytokines, antimicrobial peptides, and lysozyme-related genes. This immune profile was accompanied by enhanced mucosal barrier function and a relatively pro-inflammatory intestinal environment. In contrast, adult carp displayed increased expression of genes associated with adaptive immunity, suggesting that adult common carp exhibit relatively stronger adaptive immune characteristics than juvenile fish. Gut microbiota analysis demonstrated significant stage-dependent differences in microbial diversity and community composition. Juvenile fish were enriched with bacterial taxa potentially associated with innate immune activation, whereas adult fish harbored distinct microbial communities linked to intestinal homeostasis and barrier maintenance. Furthermore, correlation analyses identified significant associations between specific microbial taxa and innate immune-related gene expression, suggesting a close association between gut microbiota composition and intestinal immune characteristics in juvenile and adult common carp. Collectively, these findings reveal stage-associated differences in intestinal immunity and gut microbial communities between juvenile and adult common carp, thereby providing insights into intestinal immune characteristics at different developmental stages in teleost fish.

Animals↗

PubMed2025

A high-quality genomic catalog of the human oral microbiome broadens its phylogeny and clinical insights.

The oral microbiome is increasingly linked to human health. To further examine this microbial community, we present the human reference oral microbiome (HROM), with 72,641 high-quality genomes from 3,426 species, including 2,019 previously unidentified species, improving metagenomic sequence read classification over existing catalogs. Notably, HROM unveils 1,137 previously uncharacterized candidate phyla radiation (CPR) species, establishing Patescibacteria as the most prevalent phylum in the oral microbiota and distinct from environmental Patescibacteria. Additionally, an oral CPR subclade is associated with periodontitis, complementing Porphyromonas gingivalis in predicting disease. Finally, comparing HROM with reference genomes of the gut microbiome reveals taxonomic and functional divergence between these microbiomes. HROM contains 42 ectopic oral species, and their relative abundance in gut microbiota is predictive of intestinal, cardiovascular, and liver diseases. Thus, HROM offers an expanded view of the oral microbiome and highlights the clinical importance of further examining the links between oral microbes and systemic disorders.

Humans↗

PubMed2026

Opposite metabolic and gut responses to oral glutamine in male and female mice with diet-induced obesity.

Obesity is often associated with sex-dependent metabolic complications, to which altered intestinal barrier function and gut microbiota contribute. Glutamine supplementation has previously shown beneficial effects on gut barrier function and glycemic control. We thus aimed to characterize, in male and female mice, the effects of oral glutamine supplementation during high-fat-diet-induced obesity. Male and female C57BL/6 mice received a standard (SD) or high-fat diet (HFD; 60 % kcal from fat) for 14 weeks (W14). From W12 onward, mice received glutamine in drinking water (2 g/kg/day) or no supplementation. Body composition, glucose tolerance, insulin sensitivity, intestinal permeability, colonic inflammatory response, cecal microbiota and inflammatory/endocrine adipose response were assessed. In both male and female mice, glutamine supplementation failed to improve body weight and body composition. However, glutamine reduced glucose intolerance in HFD-fed males (AUC reduced by 14.57 %) that was associated with a partial restoration of plasma resistin and insulin and a trend toward limiting adipose inflammatory response. In males, glutamine did not affect gut microbiota composition and colonic response. Conversely, in HFD-fed females, glutamine supplementation led to gut microbiota changes (increase in Bacteroidota and Pseudomonadota phyla; increase in Muribaculaceae and Tannerellaceae families), increased colonic inflammatory markers (Il1b, Tlr4, Myd88, Irf3), increased inflammatory response in subcutaneous adipose tissue and increased HOMA-IR. Finally, HFD-fed mice exhibited sex-specific responses to glutamine supplementation with protective effects in males and harmful effects in females that need to be further deeply explored.

Animals↗

PubMed2004

Development of an extensive set of 16S rDNA-targeted primers for quantification of pathogenic and indigenous bacteria in faecal samples by real-time PCR.

AIMS: The microbiota of the human intestinal tract constitutes a complex ecosystem. We report the design and optimization of an extensive set of 16S rDNA-targeted species- and group-specific primers for more accurate quantification of bacteria from faecal samples with real-time PCR. METHODS AND RESULTS: A linear range of quantification between 0.1-10 pg and 10 ng of specific target genome was obtained, which corresponds to detection of ca 30-4500 to 1.9 x 10(6)-6.0 x 10(6) target bacterial genomes. Functionality of the assays was confirmed by quantification of target bacterial DNA from faecal DNA preparations of healthy volunteers and irritable bowel syndrome (IBS) patients. Additionally, spiking of faecal preparations with Helicobacter pylori, Clostridium difficile or Campylobacter jejuni was used to confirm the accurate and sensitive quantification. CONCLUSIONS: Real-time PCR is a very sensitive and precise technique for an extensive quantitative evaluation of gut microbiota and is feasible for detection of human pathogens from faecal samples. SIGNIFICANCE AND IMPACT OF THE STUDY: To design and optimize an extensive set of real-time PCR assays targeting a large group of predominant and pathogenic GI microbial species for further use in updating the current knowledge of the putative role of gut microbiota in health and disease.

Adult↗

PubMed2005

Effect of pH on an in vitro model of gastric microbiota in enteral nutrition patients.

Patients with dysphagia due to oropharyngeal disease or cerebrovascular accident require long-term nutritional support via enteral feeding, which often results in microbial overgrowth in the upper gastrointestinal (GI) tract. Gastric acid is the primary innate defense mechanism in the stomach and has been assumed to provide an effective barrier to microbial colonization at pH values of <4. To evaluate the efficacy of gastric acid as a barrier to overgrowth, the microbiota of gastric and duodenal aspirates was assessed by culturing methods. Additionally, a fermentor-based model incorporating enteral nutrition tubing of the gastric microbiota of enteral nutrition (EN) patients was constructed to assess the effect of pH on the microbiota. Results showed that gastric acidity had a relatively small effect on the numbers of microorganisms recovered from intestinal aspirates but did influence microbiota composition. Similarly, at pH 3 in the fermentor, a complex microbiota developed in the planktonic phase and in biofilms. The effect of pH on microbiota composition was similar in aspirates and in the fermentors. Candidas and lactobacilli were aciduric, while recoveries of Escherichia coli and Klebsiella pneumoniae decreased as pH was reduced, although both were still present in significant numbers at pH 3. Only Staphylococcus aureus and Bifidobacterium adolescentis persisted at higher pH values both in vitro and in vivo. Lactate and acetate were the main organic acids detected in both aspirates and fermentors. These data show that the simulator used in this investigation was capable of modeling the effects of environmental influences on the upper GI microbiota of EN patients and that gastric pH of <4 is not sufficient to prevent microbial overgrowth in these individuals.

Bacteria↗

PubMed2026

Parasites and allergies: a complex bidirectional relationship from evolutionary origins to modern therapeutics.

Parasites and allergic diseases are linked by a complex, bidirectional relationship shaped by long-term host-parasite coevolution. This review discusses how different parasites may either promote or attenuate allergic responses through immunological, epithelial, and microbiome-mediated mechanisms. IgE-mediated immunity, mast cell activation, eosinophilia, and pruritus may have evolved as protective responses against helminths and blood-feeding ectoparasites. In contrast, modern allergies may partly reflect misdirected responses to harmless environmental antigens. The effects of parasites on allergy are not uniform and depend on parasite type, infection site, exposure intensity and chronicity, host immune status, and the degree of host-parasite adaptation. Protozoa such as Giardia intestinalis may contribute to food allergy-related manifestations by disrupting the intestinal barrier, altering gut microbiota composition, and modifying mucosal immune responses, particularly in atopic individuals. In contrast, selected helminths may attenuate allergic inflammation by inducing regulatory T and B cells, anti-inflammatory cytokines, antigen-presenting cell modulation, and IgG4-associated mechanisms that can limit IgE-mediated effector responses. Molecular similarities between parasite-derived antigens and environmental allergens, including conserved protein families and carbohydrate epitopes, may contribute to cross-reactive IgE responses and complicate allergy diagnostics. Therefore, current research is shifting from live helminth therapy toward defined parasite-derived molecules and immunomodulatory pathways that may inspire safer and more controlled therapeutic strategies. A clearer understanding of parasite-allergy interactions may improve diagnostic interpretation and support the development of new approaches to the management of allergic disease.

Humans↗

PubMed2002

Escherichia coli as a cause of diarrhea.

Escherichia coli is the best-known member of the normal microbiota of the human intestine and a versatile gastrointestinal pathogen. The varieties of E. coli that cause diarrhea are classified into named pathotypes, including enterotoxigenic, enteroinvasive, enteropathogenic and enterohemorrhagic E. coli. Individual strains of each pathotype possess a distinct set of virulence-associated characteristics that determine the clinical, pathological and epidemiological features of the diseases they cause. In the present brief review, we summarize the key distinguishing features of the major pathotypes of diarrheagenic E. coli. Knowledge of the pathogenic mechanisms of these bacteria has led to the development of rational interventions for the treatment and prevention of E. coli-induced diarrhea. In addition, investigations into E. coli virulence are providing useful insights into the origins and evolution of bacterial pathogens more generally.

Diarrhea↗

PubMed2005

Niche heterogeneity determines bacterial community structure in the termite gut (Reticulitermes santonensis).

Differences in microenvironment and interactions of microorganisms within and across habitat boundaries should influence structure and diversity of the microbial communities within an ecosystem. We tested this hypothesis using the well characterized gut tract of the European subterranean termite Reticulitermes santonensis as a model. By cloning and sequencing analysis and molecular fingerprinting (terminal restriction fragment length polymorphism), we characterized the bacterial microbiota in the major intestinal habitats - the midgut, the wall of the hindgut paunch, the hindgut fluid and the intestinal protozoa. The bacterial community was very diverse (> 200 ribotypes) and comprised representatives of several phyla, including Firmicutes (mainly clostridia, streptococci and Mycoplasmatales-related clones), Bacteroidetes, Spirochaetes and a number of Proteobacteria, all of which were unevenly distributed among the four habitats. The largest group of clones fell into the so-called Termite group 1 (TG-1) phylum, which has no cultivated representatives. The majority of the TG-1 clones were associated with the protozoa and formed two phylogenetically distinct clusters, which consisted exclusively of clones previously retrieved from the gut of this and other Reticulitermes species. Also the other clones represented lineages of microorganisms that were exclusively recovered from the intestinal tract of termites. The termite specificity of these lineages was underscored by the finding that the closest relatives of the bacterial clones obtained from R. santonensis were usually derived also from the most closely related termites. Overall, differences in diversity between the different gut habitats and the uneven distribution of individual phylotypes support conclusively that niche heterogeneity is a strong determinant of the structure and spatial organization of the microbial community in the termite gut.

Animals↗