Project description:Contamination with enterohemorrhagic Escherichia coli O157:H7 (EHEC) is a worldwide problem but there is no effective therapy available for EHEC infection. Biofilm formation is closely related with EHEC infection and is one of the mechanisms of antimicrobial resistance. Antibiofilm screening of 560 plant secondary metabolites against EHEC shows that ginkgolic acids C15:1 and C17:1 at 5 μg/ml and Ginko biloba extract at 100 μg/ml significantly inhibited EHEC biofilm formation on the surface of polystyrene, nylon membrane, and glass. Importantly, the working concentration of ginkgolic acids and G. biloba extract did not affect bacterial growth and has been known to be non-toxic to human. Transcriptional analyses showed that ginkgolic acid C15:1 repressed curli genes and prophage genes in EHEC, which were corroborated by reduced fimbriae production and biofilm reduction in EHEC. Interestingly, ginkgolic acids and G. biloba extract did not inhibit the biofilm formation of commensal E. coli K-12 strain. The current study suggests that plant secondary metabolites are important resource of biofilm inhibitors, as well as other bioactive compounds.
Project description:Contamination with enterohemorrhagic Escherichia coli O157:H7 (EHEC) is a worldwide problem but there is no effective therapy available for EHEC infection. Biofilm formation is closely related with EHEC infection and is one of the mechanisms of antimicrobial resistance. Antibiofilm screening of 560 plant secondary metabolites against EHEC shows that ginkgolic acids C15:1 and C17:1 at 5 μg/ml and Ginko biloba extract at 100 μg/ml significantly inhibited EHEC biofilm formation on the surface of polystyrene, nylon membrane, and glass. Importantly, the working concentration of ginkgolic acids and G. biloba extract did not affect bacterial growth and has been known to be non-toxic to human. Transcriptional analyses showed that ginkgolic acid C15:1 repressed curli genes and prophage genes in EHEC, which were corroborated by reduced fimbriae production and biofilm reduction in EHEC. Interestingly, ginkgolic acids and G. biloba extract did not inhibit the biofilm formation of commensal E. coli K-12 strain. The current study suggests that plant secondary metabolites are important resource of biofilm inhibitors, as well as other bioactive compounds. E. coli GeneChip Genome 2.0 Array (Affymetrix, P/N 900551, Santa Clara, USA) was used to study the differential gene expression of the E. coli O157:H7 cells after the treatment with ginkgolic acid C15:1 (0.005 mg/ml). Cells were inoculated into 25 ml LB medium in 250 mL shake flasks with a starting OD600 of 0.05, and cultured at 37oC for 8 h without shaking in the presence or absence of ginkgolic acid C15:1 (5 μg/ml). To prevent RNA degradation, RNase inhibitor (RNAlater, Ambion, TX, USA) was added, and the EHEC cells were collected by centrifugation at 10,000 rpm for 1 min. The cell pellets obtained were immediately frozen with dry ice and stored at -80°C. Total RNA was isolated using a Qiagen RNeasy mini Kit (Valencia, CA, USA).
Project description:Pathogenic biofilms have been associated with persistent infections due to their high resistance to antimicrobial agents. To identify non-toxic biofilm inhibitors for enterohemorrhagic Escherichia coli O157:H7, indole-3-acetaldehyde was used and reduced E. coli O157:H7 biofilm formation. Global transcriptome analyses revealed that indole-3-acetaldehyde most repressed two curli operons, csgBAC and csgDEFG, and induced tryptophanase (tnaAB) in E. coli O157:H7 biofilm cells. Electron microscopy showed that indole-3-acetaldehyde reduced curli production in E. coli O157:H7. Together, this study shows that Actinomycetales are an important resource of biofilm inhibitors as well as antibiotics.
Project description:The transcriptome of Escherichia coli K-12 has been widely studied over a variety of conditions for the past decade while such studies involving E. coli O157:H7, its pathogenic cousin, are just now being conducted. To better understand the impact of intracellular life within a ruminant and environmental protozoan on E. coli O157:H7, global transcript levels of strain EDL933 cells inside Acanthamoeba were compared to cell grown in the protozoan media (ATCC PYG712) by microarray.
Project description:The transcriptome of Escherichia coli K-12 has been widely studied over a variety of conditions for the past decade while such studies involving E. coli O157:H7, its pathogenic cousin, are just now being conducted. To better understand the impact of an anaerobic environment on E. coli O157:H7, global transcript levels of strain EDL933 cells grown aerobically were compared to cells grown anaerobically using microarrays.
Project description:The transcriptome of Escherichia coli K-12 has been widely studied over a variety of conditions for the past decade while such studies involving E. coli O157:H7, its pathogenic cousin, are just now being conducted. To better understand the impact of heat shock on E. coli O157:H7, global transcript levels of strain EDL933 cells shifted from 37°C to 50°C for 15 min were compared to cells left at 37°C using microarrays. Keywords: Stress Response
Project description:Intercellular signal indole and its derivative hydroxyindoles inhibit Escherichia coli biofilm and diminish Pseudomonas aeruginosa virulence. However, indole and bacterial indole derivatives were unstable in microbial community due to the widespread of diverse oxygenases that could quickly degrade them. Hence, we sought to identify novel non-toxic, stable, and potent indole derivatives from plant sources for inhibiting biofilm formation of E. coli O157:H7 and P. aeruginosa PAO1. Here, plant auxin 3-indolylacetonitrile (IAN) was found to inhibit biofilm formation of both E. coli O157:H7 and P. aeruginosa without affecting its growth. IAN inhibited biofilms more effectively than indole for both E. coli and P. aeruginosa. Additionally, IAN decreased the production of virulence factor pyocyanin in P. aeruginosa. DNA microarray analysis indicated that IAN repressed genes involved in curli formation and glycerol metabolism, while IAN induced indole-related genes and prophage genes in E. coli. It appears that IAN inhibits biofilm formation of E. coli by reducing curli formation and inducing indole production. Furthermore, unlike bacterial indole derivatives, plant-originated IAN was stable in the presence of either E. coli or P. aeruginosa.
Project description:Pathogenic biofilms have been associated with persistent infections due to high resistance to antimicrobial agents while commensal biofilms often fortify host immune system. Hence, controlling biofilm formation of both pathogenic bacteria and commensal bacteria is important in bacteria-related diseases. We investigated the effect of plant flavonoids on biofilm formation of both enterohemorrhagic Escherichia coli O157:H7 and three commensal E. coli K-12 strains. Phloretin abundant in apples markedly reduced E. coli O157:H7 biofilm formation without affecting the growth of planktonic cells while phloretin did not harm commensal E. coli K-12 biofilms. Also, phloretin reduced E. coli O157:H7 attachment to human colon epithelial cells. Global transcriptome analyses revealed that phloretin repressed toxin genes (hlyE and stx2), autoinducer-2 importer genes (lsrACDBF), a curli gene (csgA), and a dozens of prophage genes in E. coli O157:H7 cells. Electron microscopy confirmed that phroretin reduced the curli production in E. coli O157:H7. In addition, phloretin suppressed TNF-α-induced inflammatory response in vitro using human colonic epithelial cells. Moreover, in the trinitrobenzene sulfonic acid (TNBS)-induced rat colitis model, phloretin significantly ameliorated colon inflammation and body weight loss. Taken together, our results suggest that phloretin may act as an inhibitor of E. coli O157:H7 biofilm formation as well as anti-inflammatory agent on inflammatory bowel diseases while leaving beneficial commensal E. coli biofilm intact.
Project description:The transcriptome of Escherichia coli K-12 has been widely studied over a variety of conditions for the past decade while such studies involving E. coli O157:H7, its pathogenic cousin, are just now being conducted. To better understand the impact of rumen fluid on E. coli O157:H7, global transcript levels of strain EDL933 cells resuspended in heat clarified rumen fluid for 15 min were compared to cells resuspended in fresh LB using microarrays.
Project description:The human intestinal microbiota associated with rats produces in vivo a soluble(s) factor(s) that down-regulates the expression of genes encoding for the Shiga toxin II in E. coli O157:H7. The Shiga toxin II is one of the major virulence factors of E. coli enterohemorragic leading to the deadly hemolitic and uremic syndrome. Investigation of the effect of the human intestinal microbiota on the whole transcriptome of EHEC O157:H7 is of major importance to increase our understanding of the pathogen transcriptomic adaptation in response to the human microbiota. We analysed by microarray hybridization the gene expression pattern of EHEC O157:H7 grown in the caecal content of germ-free rats or rats associated with the human microbiota of a healthy human subject. By doing so, we increased our understanding of the regulatory activities of the human gut microbiota on E. coli O157:H7