scholarly journals Different evolutionary trends form the twilight zone of the bacterial pan-genome

2021 ◽  
Author(s):  
Gal Horesh ◽  
Alyce Taylor-Brown ◽  
Stephanie McGimpsey ◽  
Florent Lassalle ◽  
Jukka Corander ◽  
...  
Keyword(s):  
Population Structure ◽  
Evolutionary Dynamics ◽  
Bacterial Species ◽  
Resistance Mechanisms ◽  
E Coli ◽  
Pan Genome ◽  
Metabolic Versatility ◽  
Species Population ◽  
Genome Analyses ◽  
Uneven Sampling

AbstractThe pan-genome is defined as the combined set of all genes in the gene pool of a species. Pan-genome analyses have been very useful in helping to understand different evolutionary dynamics of bacterial species: an open pan-genome often indicates a free-living lifestyle with metabolic versatility, while closed pan-genomes are linked to host-restricted, ecologically specialised bacteria. A detailed understanding of the species pan-genome has also been instrumental in tracking the phylodynamics of emerging drug resistance mechanisms and drug resistant pathogens. However, current approaches to analyse a species’ pan-genome do not take the species population structure into account, nor do they account for the uneven sampling of different lineages, as is commonplace due to over-sampling of clinically relevant representatives. Here we present the application of a population structure-aware approach for classifying genes in a pan-genome based on within-species distribution. We demonstrate our approach on a collection of 7,500 E. coli genomes, one of the most-studied bacterial species used as a model for an open pan-genome. We reveal clearly distinct groups of genes, clustered by different underlying evolutionary dynamics, and provide a more biologically informed and accurate description of the species’ pan-genome.

scholarly journals Different evolutionary trends form the twilight zone of the bacterial pan-genome

2021 ◽  
Vol 7 (9) ◽  
Author(s):  
Gal Horesh ◽  
Alyce Taylor-Brown ◽  
Stephanie McGimpsey ◽  
Florent Lassalle ◽  
Jukka Corander ◽  
...  
Keyword(s):  
Population Structure ◽  
Evolutionary Dynamics ◽  
Bacterial Species ◽  
Resistance Mechanisms ◽  
Content Type ◽  
Pan Genome ◽  
Metabolic Versatility ◽  
Species Population ◽  
Genome Analyses ◽  
Uneven Sampling

The pan-genome is defined as the combined set of all genes in the gene pool of a species. Pan-genome analyses have been very useful in helping to understand different evolutionary dynamics of bacterial species: an open pan-genome often indicates a free-living lifestyle with metabolic versatility, while closed pan-genomes are linked to host-restricted, ecologically specialized bacteria. A detailed understanding of the species pan-genome has also been instrumental in tracking the phylodynamics of emerging drug resistance mechanisms and drug-resistant pathogens. However, current approaches to analyse a species’ pan-genome do not take the species population structure into account, nor do they account for the uneven sampling of different lineages, as is commonplace due to over-sampling of clinically relevant representatives. Here we present the application of a population structure-aware approach for classifying genes in a pan-genome based on within-species distribution. We demonstrate our approach on a collection of 7500 Escherichia coli genomes, one of the most-studied bacterial species and used as a model for an open pan-genome. We reveal clearly distinct groups of genes, clustered by different underlying evolutionary dynamics, and provide a more biologically informed and accurate description of the species’ pan-genome.

scholarly journals Comparative Genome Analyses of Vibrio anguillarum Strains Reveal a Link with Pathogenicity Traits

mSystems ◽  
2017 ◽  
Vol 2 (1) ◽  
Author(s):  
Daniel Castillo ◽  
Paul D. Alvise ◽  
Ruiqi Xu ◽  
Faxing Zhang ◽  
Mathias Middelboe ◽  
...  
Keyword(s):  
Virulence Factors ◽  
Bacterial Species ◽  
Vibrio Anguillarum ◽  
Genomic Diversity ◽  
Comparative Genome ◽  
Accessory Genome ◽  
Pan Genome ◽  
Virulent Strains ◽  
Genome Analyses ◽  
Unique Core

ABSTRACT Comparative genome analysis of strains of a pathogenic bacterial species can be a powerful tool to discover acquisition of mobile genetic elements related to virulence. Here, we compared 28 V. anguillarum strains that differed in virulence in fish larval models. By pan-genome analyses, we found that six of nine highly virulent strains had a unique core and accessory genome. In contrast, V. anguillarum strains that were medium to nonvirulent had low genomic diversity. Integration of genomic and phenotypic features provides insights into the evolution of V. anguillarum and can also be important for survey and diagnostic purposes. Vibrio anguillarum is a marine bacterium that can cause vibriosis in many fish and shellfish species, leading to high mortalities and economic losses in aquaculture. Although putative virulence factors have been identified, the mechanism of pathogenesis of V. anguillarum is not fully understood. Here, we analyzed whole-genome sequences of a collection of V. anguillarum strains and compared them to virulence of the strains as determined in larval challenge assays. Previously identified virulence factors were globally distributed among the strains, with some genetic diversity. However, the pan-genome revealed that six out of nine high-virulence strains possessed a unique accessory genome that was attributed to pathogenic genomic islands, prophage-like elements, virulence factors, and a new set of gene clusters involved in biosynthesis, modification, and transport of polysaccharides. In contrast, V. anguillarum strains that were medium to nonvirulent had a high degree of genomic homogeneity. Finally, we found that a phylogeny based on the core genomes clustered the strains with moderate to no virulence, while six out of nine high-virulence strains represented phylogenetically separate clusters. Hence, we suggest a link between genotype and virulence characteristics of Vibrio anguillarum, which can be used to unravel the molecular evolution of V. anguillarum and can also be important from survey and diagnostic perspectives. IMPORTANCE Comparative genome analysis of strains of a pathogenic bacterial species can be a powerful tool to discover acquisition of mobile genetic elements related to virulence. Here, we compared 28 V. anguillarum strains that differed in virulence in fish larval models. By pan-genome analyses, we found that six of nine highly virulent strains had a unique core and accessory genome. In contrast, V. anguillarum strains that were medium to nonvirulent had low genomic diversity. Integration of genomic and phenotypic features provides insights into the evolution of V. anguillarum and can also be important for survey and diagnostic purposes.

scholarly journals Tolerance to Glutaraldehyde in Escherichia coli Mediated by Overexpression of the Aldehyde Reductase YqhD by YqhC

2021 ◽  
Vol 12 ◽  
Author(s):  
Beatriz Merchel Piovesan Pereira ◽  
Muhammad Adil Salim ◽  
Navneet Rai ◽  
Ilias Tagkopoulos
Keyword(s):  
Escherichia Coli ◽  
Bacterial Resistance ◽  
Bacterial Species ◽  
Resistance Mechanisms ◽  
Aldehyde Reductase ◽  
Tolerance Mechanism ◽  
Adaptive Laboratory Evolution ◽  
E Coli ◽  
Reductase Gene ◽  
Selection Of

Glutaraldehyde is a widely used biocide on the market for about 50 years. Despite its broad application, several reports on the emergence of bacterial resistance, and occasional outbreaks caused by poorly disinfection, there is a gap of knowledge on the bacterial adaptation, tolerance, and resistance mechanisms to glutaraldehyde. Here, we analyze the effects of the independent selection of mutations in the transcriptional regulator yqhC for biological replicates of Escherichia coli cells subjected to adaptive laboratory evolution (ALE) in the presence of glutaraldehyde. The evolved strains showed improved survival in the biocide (11–26% increase in fitness) as a result of mutations in the activator yqhC, which led to the overexpression of the yqhD aldehyde reductase gene by 8 to over 30-fold (3.1–5.2 log2FC range). The protective effect was exclusive to yqhD as other aldehyde reductase genes of E. coli, such as yahK, ybbO, yghA, and ahr did not offer protection against the biocide. We describe a novel mechanism of tolerance to glutaraldehyde based on the activation of the aldehyde reductase YqhD by YqhC and bring attention to the potential for the selection of such tolerance mechanism outside the laboratory, given the existence of YqhD homologs in various pathogenic and opportunistic bacterial species.

scholarly journals Genomic epidemiology and evolution of Escherichia coli in wild animals

2020 ◽  
Author(s):  
Robert Murphy ◽  
Martin Palm ◽  
Ville Mustonen ◽  
Jonas Warringer ◽  
Anne Farewell ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Population Structure ◽  
Host Species ◽  
Bacterial Species ◽  
Clinical Importance ◽  
Wild Animal ◽  
Whole Genome ◽  
Wild Animals ◽  
E Coli ◽  
Wild Hosts

AbstractEscherichia coli is a common bacterial species in the gastrointestinal tracts of warm-blooded animals and humans. Pathogenic and antimicrobial resistance in E. coli may emerge via host switching from animal reservoirs. Despite its potential clinical importance, knowledge of the population structure of commensal E. coli within wild hosts and the epidemiological links between E. coli in non-human hosts and E. coli in humans is still scarce. In this study, we analysed the whole genome sequencing data of a collection of 119 commensal E. coli recovered from the guts of 68 mammal and bird species in Mexico and Venezuela in the 1990s. We observed low concordance between the population structures of E. coli colonizing wild animals and the phylogeny, taxonomy and ecological and physiological attributes of the host species, with distantly related E. coli often colonizing the same or similar host species and distantly related host species often hosting closely related E. coli. We found no evidence for recent transmission of E. coli genomes from wild animals to either domesticated animals or humans. However, multiple livestock- and human-related virulence factor genes were present in E. coli of wild animals, including virulence factors characteristic for Shiga toxin-producing E. coli (STEC) and atypical enteropathogenic E. coli (aEPEC), where several isolates from wild hosts harboured the locus of enterocyte effacement (LEE) pathogenicity island. Moreover, E. coli in wild animal hosts often harboured known antibiotic resistance determinants, including against ciprofloxacin, aminoglycosides, tetracyclines and beta-lactams, with some determinants present in multiple, distantly related E. coli lineages colonizing very different host animals. We conclude that although the genome pools of E. coli colonizing wild animal and human gut are well separated, they share virulence and antibiotic resistance genes and E. coli underscoring that wild animals could serve as reservoirs for E. coli pathogenicity in human and livestock infections.ImportanceEscherichia coli is a clinically importance bacterial species implicated in human and livestock associated infections worldwide. The bacterium is known to reside in the guts of humans, livestock and wild animals. Although wild animals are recognized to serve as potential reservoirs for pathogenic E. coli strains, the knowledge of the population structure of E. coli in wild hosts is still scarce. In this study we used the fine resolution of whole genome sequencing to provide novel insights into the evolution of E. coli genomes within a broad range of wild animal species (including mammals and birds), the co-evolution of E. coli strains with their hosts and the genetics of pathogenicity of E. coli strains in wild hosts. Our results provide evidence for the clinical importance of wild animals as reservoirs for pathogenic strains and necessitate the inclusion of non-human hosts in the surveillance programs for E. coli infections.

On the island of Zanzibar people in the community are frequently colonized with the same MDR Enterobacterales found in poultry and retailed chicken meat

2020 ◽  
Vol 75 (9) ◽  
pp. 2432-2441 ◽  
Author(s):  
Thomas Büdel ◽  
Esther Kuenzli ◽  
Edgar I Campos-Madueno ◽  
Ali Haji Mohammed ◽  
Nadir Khatib Hassan ◽  
...  
Keyword(s):  
Core Genome ◽  
Resistance Mechanisms ◽  
Chicken Meat ◽  
Published Data ◽  
Single Nucleotide Variants ◽  
Single Nucleotide ◽  
E Coli ◽  
Gut Colonization ◽  
Genome Analyses ◽  
Retail Chicken Meat

Abstract Objectives Intestinal colonization with extended-spectrum cephalosporin-resistant (ESC-R) and colistin-resistant (CST-R) Enterobacterales (Ent) can be driven by contact with colonized animals and/or contamination of the food chain. We studied the ESC-R-Ent and COL-R-Ent colonizing poultry as well as contaminating chicken meat in Zanzibar (Tanzania). Results were compared with recently published data obtained from rectal swabs of people in the community. Methods During June and July 2018, we collected poultry faecal material (n = 62) and retail chicken meat (n = 37) samples. ESC-R and CST-R strains were isolated implementing selective approaches and characterized with different molecular methods, including WGS coupled with core-genome analyses. Results The prevalence of ESC-R-Ent and CST-R-Ent, respectively, were: 88.7% and 48.4% in poultry; and 43.2% and 18.9% in chicken meat. Overall, the following strains and main resistance mechanisms were found in the two settings: 69 ESC-R Escherichia coli (CTX-M-15 subgroup, 75%), 34 ESC-R Klebsiella pneumoniae (CTX-M-9 group, 54.5%), 24 non-ESC-R but CST-R E. coli (mcr-1, 95.8%) and 17 non-ESC-R but CST-R K. pneumoniae (D150G substitution in PhoQ). Several clones (differing by only 0–13 single nucleotide variants) were concomitantly and frequently found in human and non-human settings: mcr-1-carrying E. coli ST46; CTX-M-15-producing E. coli ST361; CTX-M-14-producing K. pneumoniae ST17; and CTX-M-15-producing K. pneumoniae ST1741. Conclusions This is one of the few studies that have assessed the occurrence of identical MDR Enterobacterales in human and non-human settings. The frequent human gut colonization observed in the community might be favoured by the spread of ESC-R-Ent and CST-R-Ent in poultry and chicken meat. Further studies with a One Health approach should be carried out to better investigate this phenomenon.

scholarly journals Impermanence of bacterial clones

2015 ◽  
Vol 112 (29) ◽  
pp. 8893-8900 ◽  
Author(s):  
Louis-Marie Bobay ◽  
Charles C. Traverse ◽  
Howard Ochman
Keyword(s):  
Escherichia Coli ◽  
Population Structure ◽  
Homologous Recombination ◽  
Bacterial Species ◽  
Reproductive Mode ◽  
Unique Sequence ◽  
Gene Exchange ◽  
E Coli ◽  
Large Samples ◽  
Single Genome

Bacteria reproduce asexually and pass on a single genome copied from the parent, a reproductive mode that assures the clonal descent of progeny; however, a truly clonal bacterial species is extremely rare. The signal of clonality can be interrupted by gene uptake and exchange, initiating homologous recombination that results in the unique sequence of one clone being incorporated into another. Because recombination occurs sporadically and on local scales, these events are often difficult to recognize, even when considering large samples of completely sequenced genomes. Moreover, several processes can produce the appearance of clonality in populations that undergo frequent recombination. The rates and consequences of recombination have been studied inEscherichia colifor over 40 y, and, during this time, there have been several shifting views of its clonal status, population structure, and rates of gene exchange. We reexamine the studies and retrace the evolution of the methods that have assessed the extent of DNA flux, largely focusing on its impact on theE. coligenome.

scholarly journals Hotspot Dosages of Most Rapid Antibiotic Resistance Evolution

2019 ◽  
Author(s):  
Carlos Reding ◽  
Pablo Catalán ◽  
Gunther Jansen ◽  
Tobias Bergmiller ◽  
Phillip Rosenstiel ◽  
...  
Keyword(s):  
Evolutionary Dynamics ◽  
Resistance Mechanisms ◽  
Antibiotic Resistant ◽  
E Coli ◽  
Resistance Evolution ◽  
Universal Feature ◽  
Media Adaptation ◽  
Number Variation ◽  
Selection For ◽  
Dose Dependent

We treated Escherichia coli with the antibiotic erythromycin from zero to high dosages to determine how the evolutionary dynamics of antibiotic resistant phenotypes and genotypes depend on dose. The most rapid increase in resistance was observed just below erythromycin’s minimal inhibitory concentration (MIC) and genotype-phenotype correlations determined from whole genome sequencing revealed the molecular basis of this: simultaneous selection for copy number variation in 3 resistance mechanisms which shared an ‘inverted-U’ pattern of dose-dependent selection with several insertion sequences and an integron. Many genes did not conform to this pattern, however, because of changes in selection as dose increased: media adaptation at zero-to-low dosages gave way to drug target (ribosomal RNA operon) amplification at mid dosages whereas prophage-mediated drug efflux dominated at higher dosages where population densities were lowest. All dosages saw E. coli amplify the efflux operons acr and emrE at rates that correlated strongly with changes in population density that exhibited an inverted-U geometry too. However, we show by example that inverted-U geometries are not a universal feature of dose-resistance relationships.

scholarly journals Viability and stability ofEscherichiacoliand enterococci populations in fecal samples upon freezing

2015 ◽  
Vol 61 (7) ◽  
pp. 495-501 ◽  
Author(s):  
N. Masters ◽  
M. Christie ◽  
H. Stratton ◽  
M. Katouli
Keyword(s):  
Escherichia Coli ◽  
Population Structure ◽  
Host Species ◽  
Bacterial Species ◽  
Short Term ◽  
Fecal Samples ◽  
E Coli ◽  
Short Term Storage ◽  
Before And After ◽  
Term Storage

We studied the survival of Escherichia coli and enterococci populations in fecal samples of 7 host species after storage at –20 and –80 °C for 30 days. Composite fecal samples were collected from cows, chickens, horses, pigs, dogs, birds, and humans, and bacteria were enumerated before and after storage. Twenty-eight colonies of each bacterial species were typed before and after storage and the strains were assigned to different biochemical phenotypes (BPTs). A significant reduction in the number of E. coli was observed in all samples stored at –20 °C but in only 3 of those samples stored at –80 °C. However, the numbers of enterococci were similar in most stored samples (except cow and birds). The number and the distribution of E. coli and enterococci BPTs in fresh samples did not vary significantly from those stored at either temperature. Furthermore, the population structure of E. coli and enterococci did not change significantly after storage at –80 °C, this was always the case for those samples stored at –20 °C. We conclude that for those studies investigating E. coli or enterococci population structure, short-term storage (≤30 days) of fecal samples in a glycerol broth at –80 °C is a preferable option.

The E phylogroup of Escherichia coli is highly diverse and mimics the whole E. coli species population structure

2021 ◽  
Author(s):  
Olivier Clermont ◽  
Bénédicte Condamine ◽  
Sara Dion ◽  
David M Gordon ◽  
Erick Denamur
Keyword(s):  
Escherichia Coli ◽  
Population Structure ◽  
E Coli ◽  
Species Population
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