scholarly journals Vitamin Biosynthesis by Human Gut Butyrate-Producing Bacteria and Cross-Feeding in Synthetic Microbial Communities

mBio ◽  
2020 ◽  
Vol 11 (4) ◽  
Author(s):  
Eva C. Soto-Martin ◽  
Ines Warnke ◽  
Freda M. Farquharson ◽  
Marilena Christodoulou ◽  
Graham Horgan ◽  
...  
Keyword(s):  
Amino Acids ◽  
Human Colon ◽  
Growth Stimulation ◽  
Short Chain Fatty Acids ◽  
Bacterial Strains ◽  
Healthy Human ◽  
Content Type ◽  
Health Promoting

ABSTRACT We investigated the requirement of 15 human butyrate-producing gut bacterial strains for eight B vitamins and the proteinogenic amino acids by a combination of genome sequence analysis and in vitro growth experiments. The Ruminococcaceae species Faecalibacterium prausnitzii and Subdoligranulum variabile were auxotrophic for most of the vitamins and the amino acid tryptophan. Within the Lachnospiraceae, most species were prototrophic for all amino acids and several vitamins, but biotin auxotrophy was widespread. In addition, most of the strains belonging to Eubacterium rectale and Roseburia spp., but few of the other Lachnospiraceae strains, were auxotrophic for thiamine and folate. Synthetic coculture experiments of five thiamine or folate auxotrophic strains with different prototrophic bacteria in the absence and presence of different vitamin concentrations were carried out. This demonstrated that cross-feeding between bacteria does take place and revealed differences in cross-feeding efficiency between prototrophic strains. Vitamin-independent growth stimulation in coculture compared to monococulture was also observed, in particular for F. prausnitzii A2-165, suggesting that it benefits from the provision of other growth factors from community members. The presence of multiple vitamin auxotrophies in the most abundant butyrate-producing Firmicutes species found in the healthy human colon indicates that these bacteria depend upon vitamins supplied from the diet or via cross-feeding from other members of the microbial community. IMPORTANCE Microbes in the intestinal tract have a strong influence on human health. Their fermentation of dietary nondigestible carbohydrates leads to the formation of health-promoting short-chain fatty acids, including butyrate, which is the main fuel for the colonic wall and has anticarcinogenic and anti-inflammatory properties. A good understanding of the growth requirements of butyrate-producing bacteria is important for the development of efficient strategies to promote these microbes in the gut, especially in cases where their abundance is altered. The demonstration of the inability of several dominant butyrate producers to grow in the absence of certain vitamins confirms the results of previous in silico analyses. Furthermore, establishing that strains prototrophic for thiamine or folate (butyrate producers and non-butyrate producers) were able to stimulate growth and affect the composition of auxotrophic synthetic communities suggests that the provision of prototrophic bacteria that are efficient cross feeders may stimulate butyrate-producing bacteria under certain in vivo conditions.

scholarly journals Doripenem MICs andompK36Porin Genotypes of Sequence Type 258, KPC-Producing Klebsiella pneumoniae May Predict Responses to Carbapenem-Colistin Combination Therapy among Patients with Bacteremia

2014 ◽  
Vol 59 (3) ◽  
pp. 1797-1801 ◽  
Author(s):  
Ryan K. Shields ◽  
M. Hong Nguyen ◽  
Brian A. Potoski ◽  
Ellen G. Press ◽  
Liang Chen ◽  
...  
Keyword(s):  
Amino Acids ◽  
Combination Therapy ◽  
Klebsiella Pneumoniae ◽  
Sequence Type ◽  
Content Type

ABSTRACTTreatment failures of a carbapenem-colistin regimen among patients with bacteremia due to sequence type 258 (ST258), KPC-2-producingKlebsiella pneumoniaewere significantly more likely if both agents were inactivein vitro, as defined by a colistin MIC of >2 μg/ml and the presence of either a majorompK36porin mutation (guanine and alanine insertions at amino acids 134 and 135 [ins aa 134–135 GD], IS5promoter insertion [P= 0.007]) or a doripenem MIC of >8 μg/ml (P= 0.01). MajorompK36mutations among KPC-K. pneumoniaestrains are important determinants of carbapenem-colistin responsesin vitroandin vivo.

PRO-INFLAMMATORY MOLECULAR AND INFLAMMATORY MECHANISMS OF SULFUR METABOLISM IN IBD-RELEVANT CLOSTRIDIA SPECIES

2021 ◽  
Vol 27 (Supplement_1) ◽  
pp. S30-S31
Author(s):  
Gabriel Suarez ◽  
Bo Liu ◽  
Jeremy Herzog ◽  
Ryan Sartor
Keyword(s):  
Sulfur Metabolism ◽  
Cellular Respiration ◽  
Bile Acid Metabolism ◽  
Bile Salt Hydrolase ◽  
Oxygen Binding ◽  
Bacterial Strains ◽  
Healthy Human ◽  
H2s Production

Abstract Sulfur metabolism is emerging as a signature of IBD gut microbiota. Overrepresentation of sulfur-reducing bacteria (SRB) in IBD results in SRB-derived epithelial toxic H2S production that can overwhelm the body’s detoxification capacity, leading to impaired cellular respiration by inhibiting oxygen binding to mitochondrial cytochrome-c-oxidase. Butyrate potently inhibits SRBs and H2S, yet IBD patients have reduced short chain fatty acid (SCFA) production. More critically, H2S blocks butyrate oxidation, the primary energy source of colonocytes; butyrate oxidation deficiency is a defining characteristic of IBD. Since cysteine is the preferred substrate for H2S production by SRBs, a cysteine-rich environment provided by either a high protein diet or local intestinal mucus degradation promotes ideal conditions for SRB establishment and proliferation. SRBs can catabolize other sulfur-containing compounds critical for immune homeostasis and cellular health, such as taurine-conjugated bile acids and the “master antioxidant” glutathione, leading to further toxic H2S production. However, the molecular underpinnings of sulfur metabolism by specific bacterial genera is understudied in IBD. Results: Using a combination of in-vivo and in-vitro screening to detect the relative induction of interleukin 10 (IL-10) and interferon g (IFNg) by 19 resident bacterial strains isolated from a healthy human donor, we identified 4 bacterial strains that induce a low IL-10/IFNg ratio. These 4 strains (low group), but not 3 bacterial strains that induce a high IL-10/IFNg ratio, induce colitis in selectively colonized gnotobiotic Il10-/- mice (Fig.1A). Two of these 4 disease-inducing strains, Clostridium perfringens (A12) and Clostridium bolteae (B6), produce high concentrations of H2S in monoassociated mice (Fig.1B). In-vitro H2S production by these strains is dependent on cysteine (Fig.1C). C. perfringens and C. bolteae each induce colitis in monoassociated Il10-/- mice (Fig.1D). We are dissecting the sulfur metabolic pathways in C. perfringens and C. bolteae and their contribution to inflammatory processes by interrupting key genes predicted to contribute to H2S production, cysteine catabolism and bile acid metabolism. We will use these mutants in both in-vitro and in-vivo Il10 -/- gnotobiotic mice models to characterize their metabolic and inflammatory profiles. We have created several mutants using Targetron gene editing, including the dissimilatory sulfate reductase (Δdsr), a putative sulfonate membrane transporter (ΔssuA), anaerobic sulfite reductase (ΔasrA) and bile salt hydrolase (Δbsh). Conclusions: H2S producing bacterial strains can induce experimental colitis. Our planned mechanistic studies will determine the metabolic routes for H2S production by specific aggressive bacteria to guide novel therapeutic or dietary interventions to improve IBD prognosis.

scholarly journals Enterohemorrhagic Escherichia coli Colonization of Human Colonic EpitheliumIn VitroandEx Vivo

2014 ◽  
Vol 83 (3) ◽  
pp. 942-949 ◽  
Author(s):  
Steven B. Lewis ◽  
Vivienne Cook ◽  
Richard Tighe ◽  
Stephanie Schüller
Keyword(s):  
Escherichia Coli ◽  
Human Colon ◽  
Enterohemorrhagic Escherichia Coli ◽  
Care Needs ◽  
T84 Cells ◽  
Host Cell Membrane ◽  
Content Type ◽  
Colonic Biopsy

EnterohemorrhagicEscherichia coli(EHEC) is an important foodborne pathogen causing gastroenteritis and more severe complications, such as hemorrhagic colitis and hemolytic uremic syndrome. Pathology is most pronounced in the colon, but to date there is no direct clinical evidence showing EHEC binding to the colonic epithelium in patients. In this study, we investigated EHEC adherence to the human colon by usingin vitroorgan culture (IVOC) of colonic biopsy samples and polarized T84 colon carcinoma cells. We show for the first time that EHEC colonizes human colonic biopsy samples by forming typical attaching and effacing (A/E) lesions which are dependent on EHEC type III secretion (T3S) and binding of the outer membrane protein intimin to the translocated intimin receptor (Tir). A/E lesion formation was dependent on oxygen levels and suppressed under oxygen-rich culture conditions routinely used for IVOC. In contrast, EHEC adherence to polarized T84 cells occurred independently of T3S and intimin and did not involve Tir translocation into the host cell membrane. Colonization of neither biopsy samples nor T84 cells was significantly affected by expression of Shiga toxins. Our study suggests that EHEC colonizes and forms stable A/E lesions on the human colon, which are likely to contribute to intestinal pathology during infection. Furthermore, care needs to be taken when using cell culture models, as they might not reflect thein vivosituation.

Oxidation of olive oil fortified with quercetin, caffeic acid, tyrosol and hydroxytyrosol

2015 ◽  
Vol 45 (3) ◽  
pp. 493-508 ◽  
Author(s):  
Anne Kristine Etherton ◽  
Stanley T. Omaye
Keyword(s):  
Olive Oil ◽  
Caffeic Acid ◽  
Thiobarbituric Acid ◽  
Monounsaturated Fatty Acids ◽  
Polyphenolic Compounds ◽  
Thiobarbituric Acid Reactive Substance ◽  
Content Type ◽  
Health Promoting

Purpose – This paper aims to evaluate effects of the fortification of polyphenolic compound mixtures of quercetin, caffeic acid, tryrosol and hydroxytyrosol in olive oil oxidation. Design/methodology/approach – The authors measured olive oxidation initiated by copper using thiobarbituric acid reactive substance, as an indicator of lipid peroxidation. Findings – Overall, most mixture combinations exhibited oxidation similar to olive oil alone. Some mixture combinations of polyphenolic compounds acted as antioxidants; however, as the concentrations were changed, they became prooxidant in nature. Research limitations/implications – In vitro studies have limitations for extrapolation to in vivo and clinical studies. Practical implications – Such information will be useful in determining optimal concentrations and combinations of antioxidants for reducing rancidity and perhaps as models that could be used to modulate various chronic diseases that are associated with oxidative stress. Originality/value – Olive oil, along with fruits, vegetables and fish, are important constituents of health promoting diets, such as the Mediterranean diet. Active ingredients include monounsaturated fatty acids, oleic acid and a variety of antioxidants including various polyphenolic compounds.

scholarly journals Production of multiple bacteriocins, including the novel bacteriocin gassericin M, by Lactobacillus gasseri LM19, a strain isolated from human milk

2019 ◽  
Author(s):  
Enriqueta Garcia-Gutierrez ◽  
Paula M. O’Connor ◽  
Ian J. Colquhoun ◽  
Natalia M. Vior ◽  
Juan Miguel Rodríguez ◽  
...  
Keyword(s):  
Human Milk ◽  
Human Colon ◽  
Short Chain Fatty Acids ◽  
Antagonistic Activity ◽  
The Novel ◽  
Lactobacillus Gasseri ◽  
Potential Synergy ◽  
Interesting Candidate ◽  
Health Promoting

AbstractBacteriocins are antimicrobial peptides produced by bacteria and their production by health-promoting microbes is regarded as a desirable probiotic trait. We found that Lactobacillus gasseri LM19, a strain isolated from human milk, exhibits antagonistic activity against different enteropathogens and produces several bacteriocins, including a novel bacteriocin, gassericin M. These bacteriocins were purified from culture and synthesised to investigate their activity and potential synergy. L. gasseri LM19 was tested in a complex environment mimicking human colon conditions where it not only survived but expressed the seven bacteriocin genes and produced short chain fatty acids. Metagenomic analysis of these in vitro colon cultures showed that co-inoculation of L. gasseri LM19 with Clostridium perfringens gave profiles with more similarity to controls than to vessels inoculated with C. perfringens alone. This makes L. gasseri LM19 an interesting candidate for further study for maintaining homeostasis in the gut environment.

scholarly journals Clostridioides difficile-Associated Antibiotics Alter Human Mucosal Barrier Functions by Microbiome-Independent Mechanisms

2020 ◽  
Vol 64 (4) ◽  
Author(s):  
Jemila C. Kester ◽  
Douglas K. Brubaker ◽  
Jason Velazquez ◽  
Charles Wright ◽  
Douglas A. Lauffenburger ◽  
...  
Keyword(s):  
Biological Effects ◽  
Human Colon ◽  
Mucosal Barrier ◽  
Barrier Functions ◽  
Content Type ◽  
Epithelial Culture ◽  
Clostridioides Difficile ◽  
Increased Risk

ABSTRACT A clinically relevant risk factor for Clostridioides difficile-associated disease (CDAD) is recent antibiotic treatment. Although broad-spectrum antibiotics have been shown to disrupt the structure of the gut microbiota, some antibiotics appear to increase CDAD risk without being highly active against intestinal anaerobes, suggesting direct nonantimicrobial effects. We examined cell biological effects of antibiotic exposure that may be involved in bacterial pathogenesis using an in vitro germfree human colon epithelial culture model. We found a marked loss of mucosal barrier and immune function with exposure to the CDAD-associated antibiotics clindamycin and ciprofloxacin, distinct from the results of pretreatment with an antibiotic unassociated with CDAD, tigecycline, which did not reduce innate immune or mucosal barrier functions. Importantly, pretreatment with CDAD-associated antibiotics sensitized mucosal barriers to C. difficile toxin activity in primary cell-derived enteroid monolayers. These data implicate commensal-independent gut mucosal barrier changes in the increased risk of CDAD with specific antibiotics and warrant further studies in in vivo systems. We anticipate this work to suggest potential avenues of research for host-directed treatment and preventive therapies for CDAD.

Proto-oncogene abnormalities and their relationship to tumorigenicity in some human glioblastomas

1989 ◽  
Vol 71 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Hoi Sang U ◽  
Patricia Y. Kelley ◽  
James D. Hatton ◽  
Jin Y. Shew
Keyword(s):  
Gene Expression ◽  
Cell Growth ◽  
Growth Factor Receptor ◽  
Growth Stimulation ◽  
Soft Agar ◽  
R Gene ◽  
Primary Tumors ◽  
Content Type

✓ Human glioblastomas are highly malignant intracranial tumors, some of which demonstrate amplification of the epidermal growth factor-receptor (EGF-R) gene. Overexpression of this gene is seen in the majority of primary tumors; however, the role of the EGF-R gene in glial tumorigenesis is unknown. The authors explored the relationship between EGF-R gene expression and glioblastoma cell growth in vitro and in vivo and found that the level of EGF-R gene expression did not correlate with tumor cell growth either in soft agar or in the nude mouse. This suggests that the EGF-R gene is not involved in effecting direct growth stimulation in glial oncogenesis. Tumorigenesis involves differentiation arrest; therefore, the expression of several proto-oncogenes in neuroectodermal tumors was investigated to evaluate the potential involvement of the EGF-R gene in glial differentiation. A nonoverlapping expression of the N-myc and EGF-R genes was found in neuronal-derived and glial-derived tumors, respectively. This suggests that the EGF-R gene may be involved in differentiation or its arrest in glia.

scholarly journals Characterization of Phascolarctobacterium succinatutens sp. nov., an Asaccharolytic, Succinate-Utilizing Bacterium Isolated from Human Feces

2011 ◽  
Vol 78 (2) ◽  
pp. 511-518 ◽  
Author(s):  
Yohei Watanabe ◽  
Fumiko Nagai ◽  
Masami Morotomi
Keyword(s):  
Bacterial Species ◽  
Short Chain Fatty Acids ◽  
Pcr Analysis ◽  
Rrna Gene ◽  
Gi Tract ◽  
Bacterial Strains ◽  
High Sequence Identity ◽  
Healthy Human ◽  
Content Type

ABSTRACTIsolation, cultivation, and characterization of the intestinal microorganisms are important for understanding the comprehensive physiology of the human gastrointestinal (GI) tract microbiota. Here, we isolated two novel bacterial strains, YIT 12067Tand YIT 12068, from the feces of healthy human adults. Phylogenetic analysis indicated that they belonged to the same species and were most closely related toPhascolarctobacterium faeciumACM 3679T, with 91.4% to 91.5% 16S rRNA gene sequence similarities, respectively. Substrate availability tests revealed that the isolates used only succinate; they did not ferment any other short-chain fatty acids or carbohydrates tested. When these strains were cocultured with the xylan-utilizing and succinate-producing bacteriumParaprevotella xylaniphilaYIT 11841T, in medium supplemented with xylan but not succinate, their cell numbers became 2 to 3 orders of magnitude higher than those of the monoculture; succinate became undetectable, and propionate was formed. Database analysis revealed that over 200 uncultured bacterial clones from the feces of humans and other mammals showed high sequence identity (>98.7%) to YIT 12067T. Real-time PCR analysis also revealed that YIT 12067T-like bacteria were present in 21% of human fecal samples, at an average level of 3.34 × 108cells/g feces. These results indicate that YIT 12067T-like bacteria are distributed broadly in the GI tract as subdominant members that may adapt to the intestinal environment by specializing to utilize the succinate generated by other bacterial species. The phylogenetic and physiological properties of YIT 12067Tand YIT 12068 suggest that these strains represent a novel species, which we have designatedPhascolarctobacterium succinatutenssp. nov.

scholarly journals A Naturally Occurring Deletion in FliE from Salmonella enterica Serovar Dublin Results in an Aflagellate Phenotype and Defective Proinflammatory Properties

2017 ◽  
Vol 86 (1) ◽  
Author(s):  
Sebastián Sasías ◽  
Adriana Martínez-Sanguiné ◽  
Laura Betancor ◽  
Arací Martínez ◽  
Bruno D'Alessandro ◽  
...  
Keyword(s):  
Amino Acids ◽  
Dna Sequences ◽  
High Frequency ◽  
Salmonella Enterica ◽  
Wild Type ◽  
Content Type ◽  
Naturally Occurring ◽  
Salmonella Enterica Serovar Dublin

ABSTRACTSalmonella entericaserovar Dublin is adapted to cattle but is able to infect humans with high invasiveness. An acute inflammatory response at the intestine helps to preventSalmonelladissemination to systemic sites. Flagella contribute to this response by providing motility and FliC-mediated signaling through pattern recognition receptors. In a previous work, we reported a high frequency (11 out of 25) ofS. Dublin isolates lacking flagella in a collection obtained from humans and cattle. The aflagellate strains were impaired in their proinflammatory propertiesin vitroandin vivo. The aim of this work was to elucidate the underlying cause of the absence of flagella inS. Dublin isolates. We report here that class 3 flagellar genes are repressed in the human aflagellate isolates, due to impaired secretion of FliA anti-sigma factor FlgM. This phenotype is due to an in-frame 42-nucleotide deletion in thefliEgene, which codes for a protein located in the flagellar basal body. The deletion is predicted to produce a protein lacking amino acids 18 to 31. The aflagellate phenotype was highly stable; revertants were obtained only whenfliAwas artificially overexpressed combined with several successive passages in motility agar. DNA sequence analysis revealed that motile revertants resulted from duplications of DNA sequences infliEadjacent to the deleted region. These duplications produced a FliE protein of similar length to the wild type and demonstrate that amino acids 18 to 31 of FliE are not essential. The same deletion was detected inS. Dublin isolates obtained from cattle, indicating that this mutation circulates in nature.

scholarly journals The Role of Antibiotics in Modulating Virulence in Staphylococcus aureus

2017 ◽  
Vol 30 (4) ◽  
pp. 887-917 ◽  
Author(s):  
Elisabeth Hodille ◽  
Warren Rose ◽  
Binh An Diep ◽  
Sylvain Goutelle ◽  
Gerard Lina ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Immune Response ◽  
Virulence Factors ◽  
Growth Models ◽  
Case Reports ◽  
Suppressive Effect ◽  
Bacterial Strains ◽  
Content Type

SUMMARY Staphylococcus aureus is often involved in severe infections, in which the effects of bacterial virulence factors have great importance. Antistaphylococcal regimens should take into account the different effects of antibacterial agents on the expression of virulence factors and on the host's immune response. A PubMed literature search was performed to select relevant articles on the effects of antibiotics on staphylococcal toxin production and on the host immune response. Information was sorted according to the methods used for data acquisition (bacterial strains, growth models, and antibiotic concentrations) and the assays used for readout generation. The reported mechanisms underlying S. aureus virulence modulation by antibiotics were reviewed. The relevance of in vitro observations is discussed in relation to animal model data and to clinical evidence extracted from case reports and recommendations on the management of toxin-related staphylococcal diseases. Most in vitro data point to a decreased level of virulence expression upon treatment with ribosomally active antibiotics (linezolid and clindamycin), while cell wall-active antibiotics (beta-lactams) mainly increase exotoxin production. In vivo studies confirmed the suppressive effect of clindamycin and linezolid on virulence expression, supporting their utilization as a valuable management strategy to improve patient outcomes in cases of toxin-associated staphylococcal disease.

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