Harry J Flint

..This Review considers the complex interplay between the gut microbiota, diet and health...

..The impact of dietary carbohydrates, including prebiotics, on human health requires understanding of the complex relationship between diet composition, the gut microbiota and metabolic outputs...

..As a better understanding is gained of the impact of different groups of bacteria on host metabolism, the ability to manipulate the microbiota through diet should provide a route for delivering health benefits...

..These attributes help to explain the abundance of F. prausnitzii in the colonic community but also suggest factors in the gut environment that may limit its distribution...

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..At least 10 of the metagenomic inserts that carried tet(O/32/O) also carried tet(40), suggesting that tet(40), although previously undetected, may be an abundant efflux gene...

..This type of analysis therefore provides an excellent source of information on functionally important groups within the colonic microbial community...

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..The abundance of such primary degraders may often be underestimated because of the difficulty in recovering these bacteria and their nucleic acids from the insoluble substrate...

..The newly identified gene for butyryl-CoA CoA-transferase, which performs the final step in butyrate formation in most known human colonic bacteria, was not closely linked to these central pathway genes...

..By comparison, in three of five isolates that possessed only the gus gene, β-glucuronidase activity was induced...

..nov., comb. nov. ATCC 27768(T) (= NCIMB 13872(T)) (formerly Fusobacterium prausnitzii) as the type species together with ATCC 27766 and the newly isolated strains A2-165 and L2-6...

..This study suggests that a specific subset of bacteria is likely to be the primary colonizers of particular insoluble colonic substrates. For a given substrate, however, the primary colonizing species may vary between host individuals...

..5, although volunteer and temporal variability existed. Under healthy gut environmental conditions, bacterial lactate disposal seems to exceed production markedly...

..This sortase-mediated mechanism for covalent cell-wall anchoring of the cellulosome in R. flavefaciens differs from those reported thus far for any other cellulosome system...

..Oligosaccharides used as dietary prebiotics must inevitably have complex effects upon the bacterial community that include non-target organisms and the consequences of metabolic cross-feeding and changes in the gut environment...

..nov. (type strain A2-183(T)=DSM 16839(T)=NCIMB 14029(T)), Roseburia inulinivorans sp. nov. (type strain A2-194(T)=DSM 16841(T)=NCIMB 14030(T)) and Roseburia faecis sp. nov. (type strain M72/1(T)=DSM 16840(T)=NCIMB 14031(T))...

..2.1.1). These major starch-degrading enzymes thus appear to be anchored to the cell wall in this important group of human gut bacteria...

..A2-183. This suggests strongly that the newly identified group of CoA-transferases described here plays a key role in butyrate formation in the human colon...

..The abundance of E. hallii in particular in the colonic ecosystem suggests that these bacteria play important roles in preventing lactate accumulation...

..However, the effect of such diets on microbiota-derived metabolites that influence colonic health has not been established...

..More than two-hundred dockerin-containing proteins have been identified in the R. flavefaciens genome, yet the reason for the expansion of these crucial cellulosomal components is yet unknown...

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..Here the human colonic anaerobe Roseburia inulinivorans A2-194 was shown to be a transfer recipient for two conjugative transposons, Tn1545 from Eubacterium cellulosolvens and TnK10 from Clostridium saccharolyticum K10...

..Variations in the dominant metabolic type of butyrate producer between individuals or with variations in diet are not ruled out, however, and could influence butyrate supply in the large intestine...

..Genomic analyses of the gut microbiota could revolutionize our understanding of these mechanisms and provide new biotechnological tools for the conversion of polysaccharides, including lignocellulosic biomass, into monosaccharides...

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..Several different mechanisms, including mechanisms involving plasmids and conjugative transposons, appear to be involved in the horizontal transfer of tet(W) genes, but small core regions that may function as minielements are conserved...

..The latter response may be concerned with improving bacterial access to insoluble starch particles...

..Since bacterial species have different metabolic activities, specific diets have various consequences for health, dependent on the effect exerted on the bacterial population...

..5, but were not detected at pH 6.7. Inhibition of the growth of a major group of gram-negative bacteria at mildly acidic pH apparently creates niches that can be exploited by more low pH-tolerant microorganisms...

..1%, and 1.9%, respectively; P = 0.026) decreased as carbohydrate intake decreased. The abundance of butyrate-producing bacteria related to Roseburia spp. and E. rectale correlated well with the decline in fecal butyrate...

..Coumarin compounds that occur naturally in dietary plants or when supplemented in the diet probably inhibit the survival of E. coli O157 in the gut...

..The true complexity, both at a single organism and community level, of the microbial enzyme systems that allow animals to digest plant material is beginning to become apparent...

..The nonmosaic tet(32) gene was isolated from a human saliva bacterium...

..Bacteria related to E. hallii and the genera Roseburia and Faecalibacterium are therefore among the most abundant known butyrate-producing bacteria in human feces...

..Although they have the potential to be derived from diets rich in plant-based foods, evidence suggests that these compounds can be derived from the microbial fermentation of aromatic amino acids (AAAs) in the colon...

..The phylogenetic relationships between the XYN10B CBM22 or catalytic domain and related sequences from ruminal and non-ruminal bacteria and eukaryotes are reported. The xyn10B gene is shown to lack introns...

..Populations of F. prausnitzii are reported to be decreased in Crohn's disease, for example, while populations of Roseburia relatives appear to be particularly sensitive to the diet composition in human volunteer studies...

..It is therefore proposed that strain A1-86 (=DSM 17629=NCIMB 14373), isolated from human adult faeces, be formally recognized as the neotype strain of Eubacterium rectale...

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..flavefaciens...

..It is clear that only if the link between microbial diversity and metabolic functionality is firmly established, will the mechanism by which gut microbiota maintains health or contributes to disease development be elucidated...

..Enteritidis infection in the rat. Deletion of flagella did, however, disadvantage the bacterium. This may be due to the inability to produce or release the potent immunomodulating protein flagellin...

..This work also indicates that R. bromii possesses an exceptional ability to colonize and degrade starch particles when compared with previously studied amylolytic bacteria from the human colon...

..Here we review gut microbial changes associated with aging and how diet, prebiotics and probiotics may modulate the gut microbiota to maintain health in the elderly...

..Bacteria and their metabolites can interact with the host via routes involving the immune, nervous and endocrine system...

..The majority of studies to date are however potentially confounded by the effect of treatment and a reliance on established rather than de-novo disease...

..It is proposed that a novel species, Roseburia intestinalis sp. nov., be created, with strain L1-82T (= DSM 14610T = NCIMB 13810T) as the type strain...