Multicellular behavior of environmental Escherichia coli isolates grown under nutrient-poor and low-temperature conditions

Sante, Laura Di; Pugnaloni, Armanda; Biavasco, Francesca; Giovanetti, Eleonora; Vignaroli, Carla

doi:10.1016/j.micres.2018.03.004

Cited by 8 publications

(5 citation statements)

References 34 publications

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“…The observed morphotypes are similar to the rdar phenotype observed in other enterobacteria, including E. coli and Salmonella (Römling, 2005), or the abovementioned wrinkly spreader of Pseudomonas fluorescens (Rainey and Travisano, 1998). These well-known morphotypes rely on the expression of specific surface adhesins and exopolysaccharides, most notably curli and cellulose (White and Surette, 2006;Cimdins et al, 2017;Di Sante et al, 2018). A bioinformatic search for the csgA-G operon responsible for curli formation in the genome of Kva 342 revealed no match (see Methods, Table S1).…”

Section: Resultssupporting

confidence: 54%

Emergence of novel non-aggregative variants under negative frequency-dependent selection inKlebsiella variicola

Nucci,

Janaszkiewicz,

Rocha

et al. 2023

Preprint

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Klebsiella variicola is an emergent human pathogen causing numerous diverse infections, including in the urinary tract. However, little is known about the evolution and maintenance of genetic diversity in this species, the molecular mechanisms and their population dynamics. Here, we characterized the emergence of a novel rdar-like morphotype which is contingent both on the genetic background and the environment. We show that mutations in either the nitrogen assimilation control gene (nac) or the type III fimbriae regulator, mrkH, suffice to generate rdar-like colonies. These morphotypes are primarily selected for the reduced inter-cellular aggregation as a result of loss-of-function yielding reduced fimbriae expression. Additionally, these clones also display increased growth rate and reduced biofilm formation. Direct competitions between rdar and wild type clone show that mutations in mrkH provide large fitness advantages. In artificial urine, the morphotype is under strong negative frequency-dependent selection and is able to socially exploit wild type strains. An exhaustive search for mrkH mutants in public databases revealed that ca 8% of natural isolates analysed had truncated MrkH proteins many of which were due to insertions of IS elements, including a reported clinical isolate with rdar morphology. These strains were all isolated from human, mostly from urine. The decreased aggregation of these mutants could have important clinical implications as such clones could better disperse within the host allowing colonisation of other body sites and leading to systemic infections.

show abstract

Section: Resultssupporting

confidence: 54%

Emergence of novel non-aggregative variants under negative frequency-dependent selection inKlebsiella variicola

Nucci,

Janaszkiewicz,

Rocha

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…The observed morphotypes are similar to the abovementioned rdar phenotype observed in other Enterobacteria (Römling 2005 ), or the wrinkly spreader of Pseudomonas fluorescens (Rainey and Travisano 1998 ). These well-known morphotypes rely on the expression of specific surface adhesins and exopolysaccharides, most notably curli and cellulose (White and Surette 2006 , Cimdins et al 2017 , Di Sante et al 2018 ). A bioinformatic search for the csgA-G operon responsible for curli formation in the genome of Kva 342 revealed no match (see Methods, Table S1 ).…”

Section: Resultsmentioning

confidence: 99%

Emergence of novel non-aggregative variants under negative frequency-dependent selection in Klebsiella variicola

Nucci,

Janaszkiewicz,

Rocha

et al. 2023

microLife

View full text Add to dashboard Cite

Klebsiella variicola is an emergent human pathogen causing diverse infections, some of which in the urinary tract. However, little is known about the evolution and maintenance of genetic diversity in this species, the molecular mechanisms and their population dynamics. Here, we characterized the emergence of a novel rdar-like (rough and dry) morphotype which is contingent both on the genetic background and the environment. We show that mutations in either the nitrogen assimilation control gene (nac) or the type III fimbriae regulator, mrkH, suffice to generate rdar-like colonies. These morphotypes are primarily selected for the reduced inter-cellular aggregation as a result of MrkH loss-of-function which reduces type 3 fimbriae expression. Additionally, these clones also display increased growth rate and reduced biofilm formation. Direct competitions between rdar and wild type clones show that mutations in mrkH provide large fitness advantages. In artificial urine, the morphotype is under strong negative frequency-dependent selection and can socially exploit wild type strains. An exhaustive search for mrkH mutants in public databases revealed that ca 8% of natural isolates analysed had a truncated mrkH gene many of which were due to insertions of IS elements, including a reported clinical isolate with rdar morphology. These strains were rarely hypermucoid and often isolated from human, mostly from urine and blood. The decreased aggregation of these mutants could have important clinical implications as we hypothesize that such clones could better disperse within the host allowing colonisation of other body sites and potentially leading to systemic infections.

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“…The production of both components at different temperatures was observed in dairy isolates [27] and fecal isolates of E. coli [17]. The influence of environmental factors including low temperature, low osmolarity and poor carbon sources on expression of morphotypes has been reported [28].…”

Section: Discussionmentioning

confidence: 99%

Molecular Characterization and Biofilm Formation of Escherichia coli from Vegetables

Özdemir

Arslan

2021

Sakarya University Journal of Science

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Escherichia coli can cause diarrheal and extraintestinal illnesses in humans. Diarrheagenic E. coli can be transmit to human through consumption of contaminated food, including vegetables. Biofilm produced by E. coli during food processing plays a role in development of foodborne illnesses. Vegetables have often been involved in diarrheal E. coli infections. A total of 40 E. coli isolates from vegetables were tested to determine biofilm formation at 12°C, 25°C and 37°C by the crystal violet and MTT assays. All isolates were performed for the production of curli fimbriae and cellulose associated with biofilm formation on Congo red agar. Biofilm formation by the crystal violet assay at 37°C, 25°C and 12°C was detected in 87.5%, 70% and 70% of the isolates, respectively. The biomass and viability of E. coli biofilms were similar according to the results of crystal violet and MTT assays. Biofilm formation among the E. coli isolates using the crystal violet and MTT assays showed a statistically significant difference between 12°C and 25°C as well as 12°C and 37°C (p < 0.05). However, no significant difference between 25 and 37°C (p > 0.05) was obtained. Three different morhotypes (bdar, pdar and saw) were identified based on the expression of curli fimbriae and cellulose. The incidence of the bdar morhotype was 27.5% and 50% at 25°C and 37°C, respectively. Prevalence of the pdar morphotype was 50% and 70% at 25°C and 37°C, respectively. At 25°C, only one isolate (2.5%) showed the saw morphotype. All isolates tested expressed curli fimbriae or cellulose, only three of which were non-biofilm producer using the crystal violet assay. This study demonstrated that the presence of biofilm forming E. coli isolates in vegetables may cause a risk to human health and food safety.

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Multicellular behavior of environmental Escherichia coli isolates grown under nutrient-poor and low-temperature conditions

Cited by 8 publications

References 34 publications

Emergence of novel non-aggregative variants under negative frequency-dependent selection inKlebsiella variicola

Emergence of novel non-aggregative variants under negative frequency-dependent selection inKlebsiella variicola

Emergence of novel non-aggregative variants under negative frequency-dependent selection in Klebsiella variicola

Molecular Characterization and Biofilm Formation of Escherichia coli from Vegetables

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