scholarly journals Effects of Lipopolysaccharide Core Sugar Deficiency on Colanic Acid Biosynthesis in Escherichia coli

2016 ◽  
Vol 198 (11) ◽  
pp. 1576-1584 ◽  
Author(s):  
Ge Ren ◽  
Zhou Wang ◽  
Ye Li ◽  
Xiaoqing Hu ◽  
Xiaoyuan Wang
Keyword(s):  
Escherichia Coli ◽  
Acid Production ◽  
High Performance ◽  
Membrane Integrity ◽  
Biological Significance ◽  
Bacterial Cells ◽  
Content Type ◽  
E Coli ◽  
Colanic Acid ◽  
Cell Stress Response

ABSTRACTWhen 10Escherichia colimutant strains with defects in lipopolysaccharide (LPS) core biosynthesis were grown on agar medium at 30°C, four of them, the ΔwaaF, ΔwaaG, ΔwaaP, and ΔwaaBstrains, formed mucoid colonies, while the other six, the ΔwaaU, ΔwaaR, ΔwaaO, ΔwaaC, ΔwaaQ, and ΔwaaYstrains, did not. Using light microscopy with tannin mordant staining, the presence of exopolysaccharide around the cells of the mutants that formed mucoid colonies could be discerned. The ΔwaaFmutant produced the largest amounts of exopolysaccharide, regardless of whether it was grown on agar or in liquid medium. The exopolysaccharide was isolated from the liquid growth medium of ΔwaaFcells, hydrolyzed, and analyzed by high-performance liquid chromatography with an ion-exchange column, and the results indicated that the exopolysaccharide was consistent with colanic acid. When the key genes related to the biosynthesis of colanic acid, i.e.,wza,wzb,wzc, andwcaA, were deleted in the ΔwaaFbackground, the exopolysaccharide could not be produced any more, further confirming that it was colanic acid. Colanic acid could not be produced in strains in whichrcsA,rcsB,rcsD, orrcsFwas deleted in the ΔwaaFbackground, but a reduced level of colanic acid production was detected when thercsCgene was deleted, suggesting that a change of lipopolysaccharide structure in ΔwaaFcells might be sensed by the RcsCDB phosphorelay system, leading to the production of colanic acid. The results demonstrate thatE. colicells can activate colanic acid production through the RcsCDB phosphorelay system in response to a structural deficiency of lipopolysaccharide.IMPORTANCELipopolysaccharide and colanic acid are important forms of exopolysaccharide forEscherichia colicells. Their metabolism and biological significance have been investigated, but their interrelation with the cell stress response process is not understood. This study demonstrates, for the first time, thatE. colicells can activate colanic acid production through the RcsCDB phosphorelay system in response to a structural change of lipopolysaccharide, suggesting that bacterial cells can monitor the outer membrane integrity, which is essential for cell survival and damage repair.

scholarly journals Phage-Encoded Colanic Acid-Degrading Enzyme Permits Lytic Phage Infection of a Capsule-Forming Resistant Mutant Escherichia coli Strain

2014 ◽  
Vol 81 (3) ◽  
pp. 900-909 ◽  
Author(s):  
Min Soo Kim ◽  
Young Deuk Kim ◽  
Sung Sik Hong ◽  
Kwangseo Park ◽  
Kwan Soo Ko ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Acid Production ◽  
Resistant Mutant ◽  
Phage Infection ◽  
Resistant Bacteria ◽  
Lytic Phage ◽  
Content Type ◽  
E Coli ◽  
Colanic Acid

ABSTRACTIn this study, we isolated a bacteriophage T7-resistant mutant strain ofEscherichia coli(named S3) and then proceeded to characterize it. The mutant bacterial colonies appeared to be mucoid. Microarray analysis revealed that genes related to colanic acid production were upregulated in the mutant. Increases in colanic acid production by the mutant bacteria were observed whenl-fucose was measured biochemically, and protective capsule formation was observed under an electron microscope. We found a point mutation in thelongene promoter in S3, the mutant bacterium. Overproduction of colanic acid was observed in some phage-resistant mutant bacteria after infection with other bacteriophages, T4 and lambda. Colanic acid overproduction was also observed in clinical isolates ofE. coliupon phage infection. The overproduction of colanic acid resulted in the inhibition of bacteriophage adsorption to the host. Biofilm formation initially decreased shortly after infection but eventually increased after 48 h of incubation due to the emergence of the mutant bacteria. Bacteriophage PBECO4 was shown to infect the colanic acid-overproducing mutant strains ofE. coli. We confirmed that the gene product of open reading frame 547 (ORF547) of PBECO4 harbored colanic acid-degrading enzymatic (CAE) activity. Treatment of the T7-resistant bacteria with both T7 and PBECO4 or its purified enzyme (CAE) led to successful T7 infection. Biofilm formation decreased with the mixed infection, too. This procedure, using a phage cocktail different from those exploiting solely receptor differences, represents a novel strategy for overcoming phage resistance in mutant bacteria.

PBP4 and PBP5 are involved in regulating exopolysaccharide synthesis during Escherichia coli biofilm formation

Microbiology ◽  
2021 ◽  
Vol 167 (3) ◽  
Author(s):  
Sathi Mallick ◽  
Shanti Kiran ◽  
Tapas Kumar Maiti ◽  
Anindya S. Ghosh
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Type Species ◽  
Pentose Phosphate ◽  
Bacterial Cells ◽  
Surface Adhesion ◽  
Content Type ◽  
Penicillin Binding Proteins ◽  
E Coli ◽  
Link Type

Escherichia coli low-molecular-mass (LMM) Penicillin-binding proteins (PBPs) help in hydrolysing the peptidoglycan fragments from their cell wall and recycling them back into the growing peptidoglycan matrix, in addition to their reported involvement in biofilm formation. Biofilms are external slime layers of extra-polymeric substances that sessile bacterial cells secrete to form a habitable niche for themselves. Here, we hypothesize the involvement of Escherichia coli LMM PBPs in regulating the nature of exopolysaccharides (EPS) prevailing in its extra-polymeric substances during biofilm formation. Therefore, this study includes the assessment of physiological characteristics of E. coli CS109 LMM PBP deletion mutants to address biofilm formation abilities, viability and surface adhesion. Finally, EPS from parent CS109 and its ΔPBP4 and ΔPBP5 mutants were purified and analysed for sugars present. Deletions of LMM PBP reduced biofilm formation, bacterial adhesion and their viability in biofilms. Deletions also diminished EPS production by ΔPBP4 and ΔPBP5 mutants, purification of which suggested an increased overall negative charge compared with their parent. Also, EPS analyses from both mutants revealed the appearance of an unusual sugar, xylose, that was absent in CS109. Accordingly, the reason for reduced biofilm formation in LMM PBP mutants may be speculated as the subsequent production of xylitol and a hindrance in the standard flow of the pentose phosphate pathway.

scholarly journals Bacterial Secretions of Nonpathogenic Escherichia coli Elicit Inflammatory Pathways: a Closer Investigation of Interkingdom Signaling

mBio ◽  
2015 ◽  
Vol 6 (2) ◽  
Author(s):  
Amin Zargar ◽  
David N. Quan ◽  
Karen K. Carter ◽  
Min Guo ◽  
Herman O. Sintim ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Negative Feedback ◽  
Cell Contact ◽  
Bacterial Cells ◽  
Content Type ◽  
Phenotypic Differences ◽  
E Coli ◽  
Autoinducer 2 ◽  
Human Epithelial Cells

ABSTRACTThere have been many studies on the relationship between nonpathogenic bacteria and human epithelial cells; however, the bidirectional effects of the secretomes (secreted substances in which there is no direct bacterium-cell contact) have yet to be fully investigated. In this study, we use a transwell model to explore the transcriptomic effects of bacterial secretions from two different nonpathogenicEscherichia colistrains on the human colonic cell line HCT-8 using next-generation transcriptome sequencing (RNA-Seq).E. coliBL21 and W3110, while genetically very similar (99.1% homology), exhibit key phenotypic differences, including differences in their production of macromolecular structures (e.g., flagella and lipopolysaccharide) and in their secretion of metabolic byproducts (e.g., acetate) and signaling molecules (e.g., quorum-sensing autoinducer 2 [AI-2]). After analysis of differential epithelial responses to the respective secretomes, this study shows for the first time that a nonpathogenic bacterial secretome activates the NF-κB-mediated cytokine-cytokine receptor pathways while also upregulating negative-feedback components, including the NOD-like signaling pathway. Because of AI-2's relevance as a bacterium-bacterium signaling molecule and the differences in its secretion rates between these strains, we investigated its role in HCT-8 cells. We found that the expression of the inflammatory cytokine interleukin 8 (IL-8) responded to AI-2 with a pattern of rapid upregulation before subsequent downregulation after 24 h. Collectively, these data demonstrate that secreted products from nonpathogenic bacteria stimulate the transcription of immune-related biological pathways, followed by the upregulation of negative-feedback elements that may serve to temper the inflammatory response.IMPORTANCEThe symbiotic relationship between the microbiome and the host is important in the maintenance of human health. There is a growing need to further understand the nature of these relationships to aid in the development of homeostatic probiotics and also in the design of novel antimicrobial therapeutics. To our knowledge, this is the first global-transcriptome study of bacteria cocultured with human epithelial cells in a model to determine the transcriptional effects of epithelial cells in which epithelial and bacterial cells are allowed to “communicate” with each other only through diffusible small molecules and proteins. By beginning to demarcate the direct and indirect effects of bacteria on the gastrointestinal (GI) tract, two-way interkingdom communication can potentially be mediated between host and microbe.

scholarly journals Effect of Long-Term Starvation on the Survival, Recovery, and Carbon Utilization Profiles of a Bovine Escherichia coli O157:H7 Isolate from New Zealand

2014 ◽  
Vol 80 (14) ◽  
pp. 4383-4390 ◽  
Author(s):  
Ron N. Xavier ◽  
Hugh W. Morgan ◽  
Ian R. McDonald ◽  
Helen Withers
Keyword(s):  
Escherichia Coli ◽  
New Zealand ◽  
Membrane Integrity ◽  
Nutrient Level ◽  
Carbon Utilization ◽  
Content Type ◽  
E Coli ◽  
Significant Difference ◽  
Carbon Utilization Profiles ◽  
Phosphate Buffered Saline

ABSTRACTThe ability to maintain a dual lifestyle of colonizing the ruminant gut and surviving in nonhost environments once shed is key to the success ofEscherichia coliO157:H7 as a zoonotic pathogen. Both physical and biological conditions encountered by the bacteria are likely to change during the transition between host and nonhost environments. In this study, carbon starvation at suboptimal temperatures in nonhost environments was simulated by starving a New Zealand bovineE. coliO157:H7 isolate in phosphate-buffered saline at 4 and 15°C for 84 days. Recovery of starved cells on media with different nutrient availabilities was monitored under aerobic and anaerobic conditions. We found that the New Zealand bovineE. coliO157:H7 isolate was able to maintain membrane integrity and viability over 84 days and that the level of recovery depended on the nutrient level of the recovery medium as well as the starvation temperature. In addition, a significant difference in carbon utilization was observed between starved and nonstarved cells.

scholarly journals Impacts of Hematite Nanoparticle Exposure on Biomechanical, Adhesive, and Surface Electrical Properties of Escherichia coli Cells

2012 ◽  
Vol 78 (11) ◽  
pp. 3905-3915 ◽  
Author(s):  
Wen Zhang ◽  
Joseph Hughes ◽  
Yongsheng Chen
Keyword(s):  
Escherichia Coli ◽  
Electrical Properties ◽  
Current Knowledge ◽  
Statistical Significance ◽  
Spring Constant ◽  
Bacterial Cells ◽  
Kelvin Probe ◽  
Content Type ◽  
Force Microscopy ◽  
E Coli

ABSTRACTDespite a wealth of studies examining the toxicity of engineered nanomaterials, current knowledge on their cytotoxic mechanisms (particularly from a physical perspective) remains limited. In this work, we imaged and quantitatively characterized the biomechanical (hardness and elasticity), adhesive, and surface electrical properties ofEscherichia colicells with and without exposure to hematite nanoparticles (NPs) in an effort to advance our understanding of the cytotoxic impacts of nanomaterials. Both scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed thatE. colicells had noticeable deformation with hematite treatment for 45 min with a statistical significance. The hematite-treated cells became significantly harder or stiffer than untreated ones, as evidenced by indentation and spring constant measurements. The average indentation of the hematite-treatedE. colicells was 120 nm, which is significantly lower (P< 0.01) than that of the untreated cells (approximately 400 nm). The spring constant of hematite-treatedE. colicells (0.28 ± 0.11 nN/nm) was about 20 times higher than that of untreated ones (0.01 ± 0.01 nN/nm). The zeta potential ofE. colicells, measured by dynamic light scattering (DLS), was shown to shift from −4 ± 2 mV to −27 ± 8 mV with progressive surface adsorption of hematite NPs, a finding which is consistent with the local surface potential measured by Kelvin probe force microscopy (KPFM). Overall, the reported findings quantitatively revealed the adverse impacts of nanomaterial exposure on physical properties of bacterial cells and should provide insight into the toxicity mechanisms of nanomaterials.

scholarly journals Shape Changes and Interaction Mechanism of Escherichia coli Cells Treated with Sericin and Use of a Sericin-Based Hydrogel for Wound Healing

2016 ◽  
Vol 82 (15) ◽  
pp. 4663-4672 ◽  
Author(s):  
Rui Xue ◽  
Yalong Liu ◽  
Qingsong Zhang ◽  
Congcong Liang ◽  
Huazhen Qin ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Escherichia Coli ◽  
Cell Membrane ◽  
Interaction Mechanism ◽  
Bacterial Cells ◽  
Content Type ◽  
E Coli ◽  
Membrane Blebbing ◽  
Sterile Gauze

ABSTRACTTo verify the interaction mechanism between sericin andEscherichia coli, especially the morphological and structural changes in the bacterial cells, the antimicrobial activity of sericin againstE. colias a model for Gram-negative bacteria was investigated. The antibacterial activity of sericin onE. coliand the interaction mechanism were investigated in this study by analyzing the growth, integrity, and morphology of the bacterial cells following treatment with sericin. The changes in morphology and cellular compositions of bacterial cells treated with sericin were observed by an inverted fluorescence microscope, scanning electron microscopy, and transmission electron microscopy. Changes in electrical conductivity, total sugar concentration of the broth for the bacteria, and protein expression of the bacteria were determined to investigate the permeability of the cell membrane. A sericin-based hydrogel was prepared for anin vivostudy of wound dressing. The results showed that the antibacterial activity of the hydrogel increased with the increase in the concentration of sericin from 10 g/liter to 40 g/liter. The introduction of sericin induces membrane blebbing ofE. colicells caused by antibiotic action on the cell membrane. The cytoplasm shrinkage phenomenon was accompanied by blurring of the membrane wall boundaries. WhenE. colicells were treated with sericin, release of intracellular components quickly increased. The electrical conductivity assay indicated that the charged ions are reduced after exposure to sericin so that the integrity of the cell membrane is weakened and metabolism is blocked. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that sericin hinders the expression of bacterial protein. Sericin may damage the integrity of the bacterial cell membrane, thereby eventually inhibiting the growth and reproduction ofE. coli. Compared to sterile gauze, the sericin-based hydrogel promoted fibroblast cell proliferation and accelerated the formation of granulation tissues and neovessels.IMPORTANCEThe specific relationship and interaction mechanism between sericin andE. colicells were investigated and elucidated. The results show that after 12 h of treatment, sericin molecules induce membrane blebbing ofE. colicells, and the bacteria show decreases in liquidity and permeability of biological membrane, resulting in alterations in the conductivity of the culture medium and the integrity of the outer membrane. The subsequentin vivoresults demonstrate that the sericin-poly(N-isopropylacrylamide-N,N′-methylene-bis-acrylamide [NIPAm-MBA]) hydrogel accelerated wound healing compared to that with sterile gauze, which is a beneficial result for future applications in clinical medicine and the textile, food, and coating industries.

scholarly journals CsgA Production by Escherichia coli O157:H7 Alters Attachment to Abiotic Surfaces in Some Growth Environments

2011 ◽  
Vol 77 (20) ◽  
pp. 7339-7344 ◽  
Author(s):  
R. M. Goulter-Thorsen ◽  
E. Taran ◽  
I. R. Gentle ◽  
K. S. Gobius ◽  
G. A. Dykes
Keyword(s):  
Escherichia Coli ◽  
Growth Medium ◽  
Epifluorescence Microscopy ◽  
Clear Correlation ◽  
Bacterial Cells ◽  
Content Type ◽  
E Coli ◽  
Abiotic Surfaces ◽  
Significant Difference ◽  
Force Mapping

ABSTRACTThe role of curli expression in attachment ofEscherichia coliO157:H7 to glass, Teflon, and stainless steel (SS) was investigated through the creation ofcsgAknockout mutants in two isolates ofE. coliO157:H7. Attachment assays using epifluorescence microscopy and measurements of the force of adhesion of bacterial cells to the substrates using atomic force microscopy (AFM) force mapping were used to determine differences in attachment between wild-type (wt) andcsgA-negative (ΔcsgA) strains following growth in four different media. The hydrophobicity of the cells was determined using contact angle measurements (CAM) and bacterial adhesion to hydrocarbons (BATH). The attachment assay results indicated that ΔcsgAstrains attached to glass, Teflon, and SS surfaces in significantly different numbers than their wt counterparts in a growth medium-dependent fashion (P< 0.05). However, no clear correlation was seen between attachment numbers, surface type, or growth medium. No correlation was seen between BATH and CAM results (R2< 0.70). Hydrophobicity differed between the wt and ΔcsgAin some cases in a growth medium- and method-dependent fashion (P< 0.05). AFM force mapping revealed no significant difference in the forces of adhesion to glass and SS surfaces between wt and ΔcsgAstrains (P> 0.05) but a significantly greater force of adhesion to Teflon for one of the two wt strains than for its ΔcsgAcounterpart (P< 0.05). This study shows that CsgA production byE. coliO157:H7 may alter attachment behavior in some environments; however, further investigation is required in order to determine the exact relationship between CsgA production and attachment to abiotic surfaces.

scholarly journals Specific Electromagnetic Effects of Microwave Radiation on Escherichia coli

2011 ◽  
Vol 77 (9) ◽  
pp. 3017-3022 ◽  
Author(s):  
Yury Shamis ◽  
Alex Taube ◽  
Natasa Mitik-Dineva ◽  
Rodney Croft ◽  
Russell J. Crawford ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Membrane ◽  
Cell Morphology ◽  
Laser Scanning ◽  
Simulation Software ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Bacterial Cells ◽  
Content Type ◽  
E Coli

ABSTRACTThe present study investigated the effects of microwave (MW) radiation applied under a sublethal temperature onEscherichia coli. The experiments were conducted at a frequency of 18 GHz and at a temperature below 40°C to avoid the thermal degradation of bacterial cells during exposure. The absorbed power was calculated to be 1,500 kW/m3, and the electric field was determined to be 300 V/m. Both values were theoretically confirmed using CST Microwave Studio 3D Electromagnetic Simulation Software. As a negative control,E. colicells were also thermally heated to temperatures up to 40°C using Peltier plate heating. Scanning electron microscopy (SEM) analysis performed immediately after MW exposure revealed that theE. colicells exhibited a cell morphology significantly different from that of the negative controls. This MW effect, however, appeared to be temporary, as following a further 10-min elapsed period, the cell morphology appeared to revert to a state that was identical to that of the untreated controls. Confocal laser scanning microscopy (CLSM) revealed that fluorescein isothiocyanate (FITC)-conjugated dextran (150 kDa) was taken up by the MW-treated cells, suggesting that pores had formed within the cell membrane. Cell viability experiments revealed that the MW treatment was not bactericidal, since 88% of the cells were recovered after radiation. It is proposed that one of the effects of exposingE. colicells to MW radiation under sublethal temperature conditions is that the cell surface undergoes a modification that is electrokinetic in nature, resulting in a reversible MW-induced poration of the cell membrane.

scholarly journals Reconstruction of the “Archaeal” Mevalonate Pathway from the Methanogenic Archaeon Methanosarcina mazei in Escherichia coli Cells

2020 ◽  
Vol 86 (6) ◽  
Author(s):  
Ryo Yoshida ◽  
Tohru Yoshimura ◽  
Hisashi Hemmi
Keyword(s):  
Escherichia Coli ◽  
Mevalonate Pathway ◽  
Carotenoid Pigment ◽  
Bacterial Cells ◽  
Isopentenyl Pyrophosphate ◽  
Content Type ◽  
Hyperthermophilic Archaeon ◽  
E Coli ◽  
Methanosarcina Mazei ◽  
Lycopene Production

ABSTRACT The mevalonate pathway is a well-known metabolic route that provides biosynthetic precursors for myriad isoprenoids. An unexpected variety of the pathway has been discovered from recent studies on microorganisms, mainly on archaea. The most recently discovered example, called the “archaeal” mevalonate pathway, is a modified version of the canonical eukaryotic mevalonate pathway and was elucidated in our previous study using the hyperthermophilic archaeon Aeropyrum pernix. This pathway comprises four known enzymes that can produce mevalonate 5-phosphate from acetyl coenzyme A, two recently discovered enzymes designated phosphomevalonate dehydratase and anhydromevalonate phosphate decarboxylase, and two more known enzymes, i.e., isopentenyl phosphate kinase and isopentenyl pyrophosphate:dimethylallyl pyrophosphate isomerase. To show its wide distribution in archaea and to confirm if its enzyme configuration is identical among species, the putative genes of a lower portion of the pathway—from mevalonate to isopentenyl pyrophosphate—were isolated from the methanogenic archaeon Methanosarcina mazei, which is taxonomically distant from A. pernix, and were introduced into an engineered Escherichia coli strain that produces lycopene, a red carotenoid pigment. Lycopene production, as a measure of isoprenoid productivity, was enhanced when the cells were grown semianaerobically with the supplementation of mevalonolactone, which demonstrates that the archaeal pathway can function in bacterial cells to convert mevalonate into isopentenyl pyrophosphate. Gene deletion and complementation analysis using the carotenogenic E. coli strain suggests that both phosphomevalonate dehydratase and anhydromevalonate phosphate decarboxylase from M. mazei are required for the enhancement of lycopene production. IMPORTANCE Two enzymes that have recently been identified from the hyperthermophilic archaeon A. pernix as components of the archaeal mevalonate pathway do not require ATP for their reactions. This pathway, therefore, might consume less energy than other mevalonate pathways to produce precursors for isoprenoids. Thus, the pathway might be applicable to metabolic engineering and production of valuable isoprenoids that have application as pharmaceuticals. The archaeal mevalonate pathway was successfully reconstructed in E. coli cells by introducing several genes from the methanogenic or hyperthermophilic archaeon, which demonstrated that the pathway requires the same components even in distantly related archaeal species and can function in bacterial cells.

scholarly journals Potentially Pathogenic Escherichia coli Can Form a Biofilm under Conditions Relevant to the Food Production Chain

2013 ◽  
Vol 80 (7) ◽  
pp. 2042-2049 ◽  
Author(s):  
Live L. Nesse ◽  
Camilla Sekse ◽  
Kristin Berg ◽  
Karianne C. S. Johannesen ◽  
Heidi Solheim ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Food Production ◽  
Bacterial Cells ◽  
Production Chain ◽  
Content Type ◽  
E Coli ◽  
Pathogenic Escherichia Coli ◽  
Different Temperatures ◽  
Pathogenic Serotypes ◽  
Sheep Feces

ABSTRACTThe biofilm-producing abilities of potentially human-pathogenic serotypes ofEscherichia colifrom the ovine reservoir were studied at different temperatures and on different surfaces. A possible influence of the hydrophobicity of the bacterial cells, as well as the presence of two virulence factors, the Shiga toxin-encoding (Stx) bacteriophage and theeaegene, was also studied. A total of 99E. coliisolates of serotypes O26:H11, O103:H2, and O103:H25 isolated from sheep feces were included. The results show that isolates of all threeE. coliserotypes investigated can produce biofilm on stainless steel, glass, and polystyrene at 12, 20, and 37°C. There was a good general correlation between the results obtained on the different surfaces.E. coliO103:H2 isolates produced much more biofilm than those of the other two serotypes at all three temperatures. In addition, isolates of serotype O26:H11 produced more biofilm than those of O103:H25 at 37°C. The hydrophobicity of the isolates varied between serotypes and was also influenced by temperature. The results strongly indicated that hydrophobicity influenced the attachment of the bacteria rather than their ability to form biofilm once attached. Isolates with theeaegene produced less biofilm at 37°C than isolates without this gene. The presence of a Stx bacteriophage did not influence biofilm production. In conclusion, our results show that potentially human-pathogenicE. colifrom the ovine reservoir can form biofilm on various surfaces and at several temperatures relevant for food production and handling.

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