scholarly journals Biofilm Formation Protects Escherichia coli against Killing by Caenorhabditis elegans and Myxococcus xanthus

2014 ◽  
Vol 80 (22) ◽  
pp. 7079-7087 ◽  
Author(s):  
William H. DePas ◽  
Adnan K. Syed ◽  
Margarita Sifuentes ◽  
John S. Lee ◽  
David Warshaw ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Caenorhabditis Elegans ◽  
Biofilm Formation ◽  
Myxococcus Xanthus ◽  
Enteric Bacteria ◽  
Content Type ◽  
E Coli ◽  
C Elegans ◽  
The Matrix ◽  
Nutritional Environment

ABSTRACTEnteric bacteria, such asEscherichia coli, are exposed to a variety of stresses in the nonhost environment. The development of biofilms providesE. coliwith resistance to environmental insults, such as desiccation and bleach. We found that biofilm formation, specifically production of the matrix components curli and cellulose, protectedE. coliagainst killing by the soil-dwelling nematodeCaenorhabditis elegansand the predatory bacteriumMyxococcus xanthus. Additionally, matrix-encased bacteria at the air-biofilm interface exhibited ∼40-fold-increased survival afterC. elegansandM. xanthuskilling compared to the non-matrix-encased cells that populate the interior of the biofilm. To determine if nonhostEnterobacteriaceaereservoirs supported biofilm formation, we grewE. colion media composed of pig dung or commonly contaminated foods, such as beef, chicken, and spinach. Each of these medium types provided a nutritional environment that supported matrix production and biofilm formation. Altogether, we showed that common, nonhost reservoirs ofE. colisupported the formation of biofilms that subsequently protectedE. coliagainst predation.

scholarly journals Evaluating the Pathogenic Potential of Environmental Escherichia coli by Using the Caenorhabditis elegans Infection Model

2013 ◽  
Vol 79 (7) ◽  
pp. 2435-2445 ◽  
Author(s):  
Alexandra Merkx-Jacques ◽  
Anja Coors ◽  
Roland Brousseau ◽  
Luke Masson ◽  
Alberto Mazza ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Caenorhabditis Elegans ◽  
Virulence Genes ◽  
Human Health Risk ◽  
Environmental Isolates ◽  
Pathogenic Potential ◽  
Content Type ◽  
E Coli ◽  
C Elegans ◽  
Infection Assay

ABSTRACTThe detection and abundance ofEscherichia coliin water is used to monitor and mandate the quality of drinking and recreational water. Distinguishing commensal waterborneE. coliisolates from those that cause diarrhea or extraintestinal disease in humans is important for quantifying human health risk. A DNA microarray was used to evaluate the distribution of virulence genes in 148E. colienvironmental isolates from a watershed in eastern Ontario, Canada, and in eight clinical isolates. Their pathogenic potential was evaluated withCaenorhabditis elegans, and the concordance between the bioassay result and the pathotype deduced by genotyping was explored. Isolates identified as potentially pathogenic on the basis of their complement of virulence genes were significantly more likely to be pathogenic toC. elegansthan those determined to be potentially nonpathogenic. A number of isolates that were identified as nonpathogenic on the basis of genotyping were pathogenic in the infection assay, suggesting that genotyping did not capture all potentially pathogenic types. The detection of the adhesin-encoding genessfaD,focA, andfocG, which encode adhesins; ofiroN2, which encodes a siderophore receptor; ofpic, which encodes an autotransporter protein; and ofb1432, which encodes a putative transposase, was significantly associated with pathogenicity in the infection assay. Overall,E. coliisolates predicted to be pathogenic on the basis of genotyping were indeed so in theC. elegansinfection assay. Furthermore, the detection ofC. elegans-infective environmental isolates predicted to be nonpathogenic on the basis of genotyping suggests that there are hitherto-unrecognized virulence factors or combinations thereof that are important in the establishment of infection.

scholarly journals Iron Acquisition of Urinary Tract Infection Escherichia coli Involves Pathogenicity in Caenorhabditis elegans

2021 ◽  
Vol 9 (2) ◽  
pp. 310
Author(s):  
Masayuki Hashimoto ◽  
Yi-Fen Ma ◽  
Sin-Tian Wang ◽  
Chang-Shi Chen ◽  
Ching-Hao Teng
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Caenorhabditis Elegans ◽  
Large Scale ◽  
Iron Acquisition ◽  
Infection Model ◽  
High Throughput Analysis ◽  
E Coli ◽  
C Elegans ◽  
Tract Infections

Uropathogenic Escherichia coli (UPEC) is a major bacterial pathogen that causes urinary tract infections (UTIs). The mouse is an available UTI model for studying the pathogenicity; however, Caenorhabditis elegans represents as an alternative surrogate host with the capacity for high-throughput analysis. Then, we established a simple assay for a UPEC infection model with C. elegans for large-scale screening. A total of 133 clinically isolated E. coli strains, which included UTI-associated and fecal isolates, were applied to demonstrate the simple pathogenicity assay. From the screening, several virulence factors (VFs) involved with iron acquisition (chuA, fyuA, and irp2) were significantly associated with high pathogenicity. We then evaluated whether the VFs in UPEC were involved in the pathogenicity. Mutants of E. coli UTI89 with defective iron acquisition systems were applied to a solid killing assay with C. elegans. As a result, the survival rate of C. elegans fed with the mutants significantly increased compared to when fed with the parent strain. The results demonstrated, the simple assay with C. elegans was useful as a UPEC infectious model. To our knowledge, this is the first report of the involvement of iron acquisition in the pathogenicity of UPEC in a C. elegans model.

scholarly journals A Pathoadaptive Deletion in an Enteroaggregative Escherichia coli Outbreak Strain Enhances Virulence in a Caenorhabditis elegans Model

2010 ◽  
Vol 78 (9) ◽  
pp. 4068-4076 ◽  
Author(s):  
Jennifer Hwang ◽  
Lisa M. Mattei ◽  
Laura G. VanArendonk ◽  
Philip M. Meneely ◽  
Iruka N. Okeke
Keyword(s):  
Escherichia Coli ◽  
Caenorhabditis Elegans ◽  
Epithelial Cells ◽  
Genetic Material ◽  
Decarboxylase Activity ◽  
Multicopy Plasmid ◽  
Lysine Decarboxylase ◽  
Outbreak Strain ◽  
E Coli ◽  
C Elegans

ABSTRACT Enteroaggregative Escherichia coli (EAEC) strains are important diarrheal pathogens. EAEC strains are defined by their characteristic stacked-brick pattern of adherence to epithelial cells but show heterogeneous virulence and have different combinations of adhesin and toxin genes. Pathoadaptive deletions in the lysine decarboxylase (cad) genes have been noted among hypervirulent E. coli subtypes of Shigella and enterohemorrhagic E. coli. To test the hypothesis that cad deletions might account for heterogeneity in EAEC virulence, we developed a Caenorhabditis elegans pathogenesis model. Well-characterized EAEC strains were shown to colonize and kill C. elegans, and differences in virulence could be measured quantitatively. Of 49 EAEC strains screened for lysine decarboxylase activity, 3 tested negative. Most notable is isolate 101-1, which was recovered in Japan, from the largest documented EAEC outbreak. EAEC strain 101-1 was unable to decarboxylate lysine in vitro due to deletions in cadA and cadC, which, respectively, encode lysine decarboxylase and a transcriptional activator of the cadAB genes. Strain 101-1 was significantly more lethal to C. elegans than control strain OP50. Lethality was attenuated when the lysine decarboxylase defect was complemented from a multicopy plasmid and in single copy. In addition, restoring lysine decarboxylase function produced derivatives of 101-1 deficient in aggregative adherence to cultured human epithelial cells. Lysine decarboxylase inactivation is pathoadapative in an important EAEC outbreak strain, and deletion of cad genes could produce hypervirulent EAEC lineages in the future. These results suggest that loss, as well as gain, of genetic material can account for heterogeneous virulence among EAEC strains.

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 Functional Analysis of Genes Comprising the Locus of Heat Resistance in Escherichia coli

2017 ◽  
Vol 83 (20) ◽  
Author(s):  
Ryan Mercer ◽  
Oanh Nguyen ◽  
Qixing Ou ◽  
Lynn McMullen ◽  
Michael G. Gänzle
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
Heat Resistance ◽  
Growth Phase ◽  
Genomic Island ◽  
Enteric Bacteria ◽  
Content Type ◽  
E Coli ◽  
Shock Proteins

ABSTRACT The locus of heat resistance (LHR) is a 15- to 19-kb genomic island conferring exceptional heat resistance to organisms in the family Enterobacteriaceae, including pathogenic strains of Salmonella enterica and Escherichia coli. The complement of LHR-comprising genes that is necessary for heat resistance and the stress-induced or growth-phase-induced expression of LHR-comprising genes are unknown. This study determined the contribution of the seven LHR-comprising genes yfdX1 GI, yfdX2, hdeD GI, orf11, trx GI, kefB, and psiE GI by comparing the heat resistances of E. coli strains harboring plasmid-encoded derivatives of the different LHRs in these genes. (Genes carry a subscript “GI” [genomic island] if an ortholog of the same gene is present in genomes of E. coli.) LHR-encoded heat shock proteins sHSP20, ClpKGI, and sHSPGI are not sufficient for the heat resistance phenotype; YfdX1, YfdX2, and HdeD are necessary to complement the LHR heat shock proteins and to impart a high level of resistance. Deletion of trx GI, kefB, and psiE GI from plasmid-encoded copies of the LHR did not significantly affect heat resistance. The effect of the growth phase and the NaCl concentration on expression from the putative LHR promoter p2 was determined by quantitative reverse transcription-PCR and by a plasmid-encoded p2:GFP promoter fusion. The expression levels of exponential- and stationary-phase E. coli cells were not significantly different, but the addition of 1% NaCl significantly increased LHR expression. Remarkably, LHR expression in E. coli was dependent on a chromosomal copy of evgA. In conclusion, this study improved our understanding of the genes required for exceptional heat resistance in E. coli and factors that increase their expression in food. IMPORTANCE The locus of heat resistance (LHR) is a genomic island conferring exceptional heat resistance to several foodborne pathogens. The exceptional level of heat resistance provided by the LHR questions the control of pathogens by current food processing and preparation techniques. The function of LHR-comprising genes and their regulation, however, remain largely unknown. This study defines a core complement of LHR-encoded proteins that are necessary for heat resistance and demonstrates that regulation of the LHR in E. coli requires a chromosomal copy of the gene encoding EvgA. This study provides insight into the function of a transmissible genomic island that allows otherwise heat-sensitive enteric bacteria, including pathogens, to lead a thermoduric lifestyle and thus contributes to the detection and control of heat-resistant enteric bacteria in food.

scholarly journals Temporal Transcriptomics of Gut Escherichia coli in Caenorhabditis elegans Models of Aging

2021 ◽  
Author(s):  
Joshua D. Brycki ◽  
Jeremy R. Chen See ◽  
Gillian R. Letson ◽  
Cade S. Emlet ◽  
Lavinia V. Unverdorben ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Caenorhabditis Elegans ◽  
Life Span ◽  
Wild Type ◽  
Health Span ◽  
Content Type ◽  
C Elegans ◽  
Evolutionarily Conserved

Previous research has reported effects of the microbiome on health span and life span of Caenorhabditis elegans , including interactions with evolutionarily conserved pathways in humans. We build on this literature by reporting the gene expression of Escherichia coli OP50 in wild-type (N2) and three long-lived mutants of C. elegans .

scholarly journals Bioinformatic and Molecular Analysis of Inverse Autotransporters from Escherichia coli

mSphere ◽  
2019 ◽  
Vol 4 (4) ◽  
Author(s):  
Kelvin G. K. Goh ◽  
Danilo G. Moriel ◽  
Steven J. Hancock ◽  
Minh-Duy Phan ◽  
Mark A. Schembri
Keyword(s):  
Escherichia Coli ◽  
Cell Surface ◽  
Biofilm Formation ◽  
Secretion System ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Type V Secretion ◽  
K 12 ◽  
Type V

ABSTRACT Proteins secreted by the type V secretion system possess multiple functions, including the capacity to mediate adhesion, aggregation, and biolfilm formation. The type V secretion system can be divided into five subclasses, one of which is the type Ve system. Proteins of the type Ve secretion system are also referred to as inverse autotransporters (IATs). In this study, we performed an in silico analysis of 126 completely sequenced Escherichia coli genomes available in the NCBI database and identified several distinct IAT-encoding gene families whose distribution varied throughout the E. coli phylogeny. The genes included three characterized IATs (intimin, fdeC, and yeeJ) and four uncharacterized IATs (here named iatA, iatB, iatC, and iatD). The four iat genes were cloned from the completely sequenced environmental E. coli strain SMS-3-5 and characterized. Three of these IAT proteins (IatB, IatC, and IatD) were expressed at the cell surface and possessed the capacity to mediate biofilm formation in a recombinant E. coli K-12 strain. Further analysis of the iatB gene, which showed a unique association with extraintestinal E. coli strains, suggested that its regulation is controlled by the LeuO global regulator. Overall, this study provides new data describing the prevalence, sequence variation, domain structure, function, and regulation of IATs found in E. coli. IMPORTANCE Escherichia coli is one of the most prevalent facultative anaerobes of the human gut. E. coli normally exists as a harmless commensal but can also cause disease following the acquisition of genes that enhance its pathogenicity. Adhesion is an important first step in colonization of the host and is mediated by an array of cell surface components. In E. coli, these include a family of adhesins secreted by the type V secretion system. Here, we identified and characterized new proteins from an emerging subclass of the type V secretion system known as the inverse autotransporters (IATs). We found that IAT-encoding genes are present in a wide range of strains and showed that three novel IATs were localized on the E. coli cell surface and mediated biofilm formation. Overall, this study provides new insight into the prevalence, function, and regulation of IATs in E. coli.

scholarly journals Flagellum-Mediated Mechanosensing and RflP Control Motility State of Pathogenic Escherichia coli

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Leanid Laganenka ◽  
María Esteban López ◽  
Remy Colin ◽  
Victor Sourjik
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Porous Medium ◽  
Biofilm Formation ◽  
Liquid Culture ◽  
Content Type ◽  
E Coli ◽  
Surface Contact ◽  
Conditional Inhibition ◽  
Flagellar Genes

ABSTRACT Bacterial flagellar motility plays an important role in many processes that occur at surfaces or in hydrogels, including adhesion, biofilm formation, and bacterium-host interactions. Consequently, expression of flagellar genes, as well as genes involved in biofilm formation and virulence, can be regulated by the surface contact. In a few bacterial species, flagella themselves are known to serve as mechanosensors, where an increased load on flagella experienced during surface contact or swimming in viscous media controls gene expression. In this study, we show that gene regulation by motility-dependent mechanosensing is common among pathogenic Escherichia coli strains. This regulatory mechanism requires flagellar rotation, and it enables pathogenic E. coli to repress flagellar genes at low loads in liquid culture, while activating motility in porous medium (soft agar) or upon surface contact. It also controls several other cellular functions, including metabolism and signaling. The mechanosensing response in pathogenic E. coli depends on the negative regulator of motility, RflP (YdiV), which inhibits basal expression of flagellar genes in liquid. While no conditional inhibition of flagellar gene expression in liquid and therefore no upregulation in porous medium was observed in the wild-type commensal or laboratory strains of E. coli, mechanosensitive regulation could be recovered by overexpression of RflP in the laboratory strain. We hypothesize that this conditional activation of flagellar genes in pathogenic E. coli reflects adaptation to the dual role played by flagella and motility during infection. IMPORTANCE Flagella and motility are widespread virulence factors among pathogenic bacteria. Motility enhances the initial host colonization, but the flagellum is a major antigen targeted by the host immune system. Here, we demonstrate that pathogenic E. coli strains employ a mechanosensory function of the flagellar motor to activate flagellar expression under high loads, while repressing it in liquid culture. We hypothesize that this mechanism allows pathogenic E. coli to regulate its motility dependent on the stage of infection, activating flagellar expression upon initial contact with the host epithelium, when motility is beneficial, but reducing it within the host to delay the immune response.

scholarly journals The Catabolite Repressor Protein-Cyclic AMP Complex RegulatescsgDand Biofilm Formation in Uropathogenic Escherichia coli

2016 ◽  
Vol 198 (24) ◽  
pp. 3329-3334 ◽  
Author(s):  
David A. Hufnagel ◽  
Margery L. Evans ◽  
Sarah E. Greene ◽  
Jerome S. Pinkner ◽  
Scott J. Hultgren ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Extracellular Matrix ◽  
Cyclic Amp ◽  
Intergenic Region ◽  
Biofilm Formation ◽  
Cellulose Production ◽  
Content Type ◽  
E Coli ◽  
Link Type ◽  
K1 Capsule

ABSTRACTThe extracellular matrix protectsEscherichia colifrom immune cells, oxidative stress, predation, and other environmental stresses. Production of theE. coliextracellular matrix is regulated by transcription factors that are tuned to environmental conditions. The biofilm master regulator protein CsgD upregulates curli and cellulose, the two major polymers in the extracellular matrix of uropathogenicE. coli(UPEC) biofilms. We found that cyclic AMP (cAMP) regulates curli, cellulose, and UPEC biofilms throughcsgD. The alarmone cAMP is produced by adenylate cyclase (CyaA), and deletion ofcyaAresulted in reduced extracellular matrix production and biofilm formation. Thecataboliterepressorprotein (CRP) positively regulatedcsgDtranscription, leading to curli and cellulose production in the UPEC isolate, UTI89. Glucose, a known inhibitor of CyaA activity, blocked extracellular matrix formation when added to the growth medium. The mutant strains ΔcyaAand Δcrpdid not produce rugose biofilms, pellicles, curli, cellulose, or CsgD. Three putative CRP binding sites were identified within thecsgD-csgBintergenic region, and purified CRP could gel shift thecsgD-csgBintergenic region. Additionally, we found that CRP binded upstream ofkpsMT, which encodes machinery for K1 capsule production. Together our work shows that cAMP and CRP influenceE. colibiofilms through transcriptional regulation ofcsgD.IMPORTANCEThecataboliterepressorprotein (CRP)-cyclic AMP (cAMP) complex influences the transcription of ∼7% of genes on theEscherichia colichromosome (D. Zheng, C. Constantinidou, J. L. Hobman, and S. D. Minchin, Nucleic Acids Res 32:5874–5893, 2004,https://dx.doi.org/10.1093/nar/gkh908). Glucose inhibitsE. colibiofilm formation, and ΔcyaAand Δcrpmutants show impaired biofilm formation (D. W. Jackson, J.W. Simecka, and T. Romeo, J Bacteriol 184:3406–3410, 2002,https://dx.doi.org/10.1128/JB.184.12.3406-3410.2002). We determined that the cAMP-CRP complex regulates curli and cellulose production and the formation of rugose and pellicle biofilms throughcsgD. Additionally, we propose that cAMP may work as a signaling compound for uropathogenicE. coli(UPEC) to transition from the bladder lumen to inside epithelial cells for intracellular bacterial community formation through K1 capsule regulation.

scholarly journals Inactivation of Escherichia coli by Polychromatic Simulated Sunlight: Evidence for and Implications of a Fenton Mechanism Involving Iron, Hydrogen Peroxide, and Superoxide

2013 ◽  
Vol 80 (3) ◽  
pp. 935-942 ◽  
Author(s):  
Michael B. Fisher ◽  
Kara L. Nelson
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Enteric Bacteria ◽  
Growth Conditions ◽  
Simulated Sunlight ◽  
Wild Type ◽  
Intracellular Iron ◽  
Content Type ◽  
E Coli ◽  
Degree Of Sensitization

ABSTRACTSunlight inactivation ofEscherichia colihas previously been shown to accelerate in the presence of oxygen, exogenously added hydrogen peroxide, and bioavailable forms of exogenously added iron. In this study, mutants unable to effectively scavenge hydrogen peroxide or superoxide were found to be more sensitive to polychromatic simulated sunlight (without UVB wavelengths) than wild-type cells, while wild-type cells grown under low-iron conditions were less sensitive than cells grown in the presence of abundant iron. Furthermore, prior exposure to simulated sunlight was found to sensitize cells to subsequent hydrogen peroxide exposure in the dark, but this effect was attenuated for cells grown with low iron. Mutants deficient in recombination DNA repair were sensitized to simulated sunlight (without UVB wavelengths), but growth in the presence of iron chelators reduced the degree of sensitization conferred by this mutation. These findings support the hypothesis that hydrogen peroxide, superoxide, and intracellular iron all participate in the photoinactivation ofE. coliand further suggest that the inactivation rate of enteric bacteria in the environment may be strongly dependent on iron availability and growth conditions.

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