Biofilm formation by avian Escherichia coli in relation to media, source and phylogeny

Skyberg, Jerod A.; Siek, Kylie E.; Doetkott, Curt; Nolan, Lisa K.

doi:10.1111/j.1365-2672.2006.03076.x

Cited by 61 publications

(58 citation statements)

References 27 publications

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“…We initially hypothesized that high biofilm formation may be an important phenotype for survival in the soil; however, our results showed that only two soil-persistent isolates produced high levels of biofilm under the conditions investigated, suggesting that the ability to form biofilm may not be an essential phenotype for long-term soil survival. The result of the heterogeneity in biofilm production observed in our study is consistent with the study of Skyberg et al (65), which showed that biofilm production is strain specific and not significantly influenced by phylogenetic group. Similar to previous studies that have shown that biofilm formation is higher at lower temperatures (48,66) and that biofilmrelated genes are upregulated at 23°C compared to 37°C (67), we demonstrate that E. coli strains can produce high levels of biofilm at 15°C.…”

Section: Discussionsupporting

confidence: 82%

The General Stress Response Is Conserved in Long-Term Soil-Persistent Strains of Escherichia coli

Somorin

Abram

Brennan

et al. 2016

Appl Environ Microbiol

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Although Escherichia coli is generally considered to be predominantly a commensal of the gastrointestinal tract, a number of recent studies suggest that it is also capable of long-term survival and growth in environments outside the host. As the extraintestinal physical and chemical conditions are often different from those within the host, it is possible that distinct genetic adaptations may be required to enable this transition. Several studies have shown a trade-off between growth and stress resistance in nutrient-poor environments, with lesions in the rpoS locus, which encodes the stress sigma factor RpoS ( S ). In this study, we investigated a unique collection of long-term soil-persistent E. coli isolates to determine whether the RpoS-controlled general stress response is altered during adaptation to a nutrient-poor extraintestinal environment. The sequence of the rpoS locus was found to be highly conserved in these isolates, and no nonsense or frameshift mutations were detected. Known RpoS-dependent phenotypes, including glycogen synthesis and ␥-aminobutyrate production, were found to be conserved in all strains. All strains expressed the full-length RpoS protein, which was fully functional using the RpoS-dependent promoter reporter fusion PgadX:: gfp. RpoS was shown to be essential for long-term soil survival of E. coli, since mutants lacking rpoS lost viability rapidly in soil survival assays. Thus, despite some phenotypic heterogeneity, the soil-persistent strains all retained a fully functional RpoS-regulated general stress response, which we interpret to indicate that the stresses encountered in soil provide a strong selective pressure for maintaining stress resistance, despite limited nutrient availability. IMPORTANCEEscherichia coli has been, and continues to be, used as an important indicator species reflecting potential fecal contamination events in the environment. However, recent studies have questioned the validity of this, since E. coli has been found to be capable of long-term colonization of soils. This study investigated whether long-term soil-persistent E. coli strains have evolved altered stress resistance characteristics. In particular, the study investigated whether the main regulator of genes involved in stress protection, the sigma factor RpoS, has been altered in the soil-persistent strains. The results show that RpoS stress protection is fully conserved in soil-persistent strains of E. coli. They also show that loss of the rpoS gene dramatically reduces the ability of this organism to survive in a soil environment. Overall, the results indicate that soil represents a stressful environment for E. coli, and their survival in it requires that they deploy a full stress protection response. E scherichia coli is a Gram-negative, facultative anaerobe, belonging to the Enterobacteriaceae family, which inhabits the intestinal tracts of humans, warm-blooded animals, and reptiles (1, 2). It can be transferred through water and sediments via feces and is almost universally used as an i...

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Section: Discussionsupporting

confidence: 82%

The General Stress Response Is Conserved in Long-Term Soil-Persistent Strains of Escherichia coli

Somorin

Abram

Brennan

et al. 2016

Appl Environ Microbiol

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“…To examine whether the T6SS was involved in biofilm formation or not, wild-type and mutant strains were tested for their ability to form biofilms on polystyrene surfaces as previously described (41,42). The growth rates of T6SS-associated mutants were similar to those of the wild-type strain (see Fig.…”

Section: Resultsmentioning

confidence: 99%

“…3A). Since most virulence factors contributing to biofilm formation could induce intercellular autoaggregation (42), it could be inferred that the inactivation of T6SS1 reduced autoaggregation of APEC strain TW-XM. However, T6SS2 did not affect the biofilm formation.…”

Section: Resultsmentioning

confidence: 99%

Two Functional Type VI Secretion Systems in Avian Pathogenic Escherichia coli Are Involved in Different Pathogenic Pathways

Bao

Sun

et al. 2014

Infect Immun

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Type VI secretion systems (T6SSs) are involved in the pathogenicity of several Gram-negative bacteria. The VgrG protein, a core component and effector of T6SS, has been demonstrated to perform diverse functions. The N-terminal domain of VgrG protein is a homologue of tail fiber protein gp27 of phage T4, which performs a receptor binding function and determines the host specificity. Based on sequence analysis, we found that two putative T6SS loci exist in the genome of the avian pathogenic Escherichia coli (APEC) strain TW-XM. To assess the contribution of these two T6SSs to TW-XM pathogenesis, the crucial clpV clusters of these two T6SS loci and their vgrG genes were deleted to generate a series of mutants. Consequently, T6SS1-associated mutants presented diminished adherence to and invasion of several host cell lines cultured in vitro, decreased pathogenicity in duck and mouse infection models in vivo, and decreased biofilm formation and bacterial competitive advantage. In contrast, T6SS2-associated mutants presented a significant decrease only in the adherence to and invasion of mouse brain microvascular endothelial cell (BMEC) line bEnd.3 and brain tissue of the duck infection model. These results suggested that T6SS1 was involved in the proliferation of APEC in systemic infection, whereas VgrG-T6SS2 was responsible only for cerebral infection. Further study demonstrated that VgrG-T6SS2 was able to bind to the surface of bEnd.3 cells, whereas it did not bind to DF-1 (chicken embryo fibroblast) cells, which further proved the interaction of VgrG-T6SS2 with the surface of BMECs.

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“…A close relationship between virulence factors and pathogencity of APEC has been reported (Babai et al, 1997;Gomis et al, 2001;Janben et al, 2001;Kaipainen et al, 2002;Dziva & Stevens, 2008;Tyler et al, 2008). Genotyping of the virulence-associated genes has been suggested to differentiate APEC strains isolated from internal organs of poultry suffering multi-systemic infections from E. coli strains from faeces of clinically healthy chickens (Pfaff-McDonough et al, 2000;Delicato et al, 2003;McPeake et al, 2005;Rodriguez-Siek et al, 2005b;Skyberg et al, 2007;Johnson et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Distribution of serotypes and virulence-associated genes in pathogenicEscherichia coliisolated from ducks

et al. 2010

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The objective of the present study was to investigate the serotypes and virulence-associated genes of avian pathogenic Escherichia coli (APEC) isolated from duck colibacillosis cases. Two hundred and fifty-four APEC isolates from duck colibacillosis cases were serotyped and amplified for 12 known virulenceassociated genes and the betA gene (encoding choline dehydrogenase) by polymerase chain reaction assays. One hundred and forty-three E. coli isolates from cloacal swabs of healthy ducks were also amplified for the same genes. A total of 53 O-serogroups were found in 254 APEC isolates, among which O93, O78 and O92 were predominant serogroups. Polymerase chain reaction results showed that Shiga-toxin-producing E. coli distributed in only 2.4% of ducks compared with 49.2% of the APEC isolates harbouring the irp2 gene, and 44.9% the fyuA gene, respectively. The ibeA gene was only present in 27 APEC isolates and was not found in healthy ducks. The rfaH gene was detected in 20.5% of APEC isolates, whereas 5.6% was found in healthy ducks. A total 79.5% of APEC isolates harboured the betA gene, which was significantly higher than in healthy ducks (16.1%), suggesting that betA may be associated with virulence.

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Biofilm formation by avian Escherichia coli in relation to media, source and phylogeny

Cited by 61 publications

References 27 publications

The General Stress Response Is Conserved in Long-Term Soil-Persistent Strains of Escherichia coli

The General Stress Response Is Conserved in Long-Term Soil-Persistent Strains of Escherichia coli

Two Functional Type VI Secretion Systems in Avian Pathogenic Escherichia coli Are Involved in Different Pathogenic Pathways

Distribution of serotypes and virulence-associated genes in pathogenicEscherichia coliisolated from ducks

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