scholarly journals Lazarus effects: the frequency and genetic causes of Escherichia coli population recovery under lethal heat stress

2016 ◽  
Author(s):  
Shaun M. Hug ◽  
Brandon S. Gaut
Keyword(s):  
Escherichia Coli ◽  
Antagonistic Pleiotropy ◽  
Lethal Temperature ◽  
Epistatic Interactions ◽  
Genetic Changes ◽  
E Coli ◽  
Evolutionary Innovation ◽  
Fitness Benefits ◽  
Fitness Tradeoffs ◽  
Lazarus Effect

ABSTRACTSometimes populations crash and yet recover before being lost completely. Such recoveries have been observed incidentally in evolution experiments using Escherichia coli, and this phenomenon has been termed the “Lazarus effect.” To investigate how often recovery occurs and the genetic changes that drive it, we evolved ~300 populations of E. coli at lethally high temperatures (43.0°) for five days and sequenced the genomes of recovered populations. Our results revealed that the Lazarus effect is uncommon, but frequent enough, at ~9% of populations, to be a potent source of evolutionary innovation. Population sequencing uncovered a set of mutations adaptive to lethal 43.0°C that were mostly distinct from those that were beneficial at a high but nonlethal temperature (42.2°). Mutations within two operons—the heat shock hslUV operon and the RNA polymerase rpoBC operon—drove adaptation to lethal temperature. Mutations in hslUV exhibited little antagonistic pleiotropy at 37.0°C and may have arisen neutrally prior to subjection to lethal temperature. In contrast, rpoBC mutations provided greater fitness benefits than hslUV mutants, but were less prevalent and caused stronger fitness tradeoffs at lower temperatures. Recovered populations fixed mutations in only one operon or the other, but not both, indicating that epistatic interactions between beneficial mutations were important even at the earliest stages of adaptation.

scholarly journals War Wound Treatment Complications Due to Transfer of an IncN Plasmid HarboringblaOXA-181from Morganella morganii to CTX-M-27-Producing Sequence Type 131 Escherichia coli

2015 ◽  
Vol 59 (6) ◽  
pp. 3556-3562 ◽  
Author(s):  
Patrick McGann ◽  
Erik Snesrud ◽  
Ana C. Ong ◽  
Lakshmi Appalla ◽  
Michael Koren ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Carbapenem Resistance ◽  
Sequence Type ◽  
Molecular Techniques ◽  
Morganella Morganii ◽  
Genetic Changes ◽  
Content Type ◽  
Surgical Interventions ◽  
E Coli ◽  
Extended Spectrum

ABSTRACTA 22-year-old male developed a recurrent sacral abscess associated with embedded shrapnel following a blast injury. Cultures grew extended-spectrum β-lactamase (ESBL)-producing, carbapenem-susceptibleEscherichia coli. Ertapenem was administered, but the infection recurred after each course of antibiotics. Initial surgical interventions were unsuccessful, and subsequent cultures yieldedE. coliandMorganella morganii, both nonsusceptible to carbapenems. The isolates were Carba NP test negative, gave ambiguous results with the modified Hodge test, and amplified theblaOXA48-like gene by real-time PCR. AllE. coliisolates were sequence type 131 (ST131), carried nine resistance genes (includingblaCTX-M-27) on an IncF plasmid, and were identical by genome sequencing, except for 150 kb of plasmid DNA in carbapenem-nonsusceptible isolates only. Sixty kilobases of this was shared byM. morganiiand represented an IncN plasmid harboringblaOXA-181. InM. morganii, the gene was flanked by IS3000and ISKpn19, but in all but one of theE. coliisolates containingblaOXA-181, a second copy of ISKpn19had inserted adjacent to IS3000. To the best of our knowledge, this is the first report ofblaOXA-181in the virulent ST131 clonal group and carried by the promiscuous IncN family of plasmids. The tendency ofM. morganiito have high MICs of imipenem, ablaOXA-181substrate profile that includes penicillins but not extended-spectrum cephalosporins, and weak carbapenemase activity almost resulted in the presence ofblaOXA-181being overlooked. We highlight the importance of surveillance for carbapenem resistance in all species, even those with intrinsic resistances, and the value of advanced molecular techniques in detecting subtle genetic changes.

scholarly journals Associations between the Presence of Virulence Determinants and the Epidemiology and Ecology of Zoonotic Escherichia coli

2010 ◽  
Vol 76 (24) ◽  
pp. 8110-8116 ◽  
Author(s):  
K. M. O'Reilly ◽  
J. C. Low ◽  
M. J. Denwood ◽  
D. L. Gally ◽  
J. Evans ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Dynamic Models ◽  
Transmission Rate ◽  
Human Infection ◽  
Virulence Determinants ◽  
Reproduction Ratio ◽  
E Coli ◽  
Enhanced Transmission ◽  
Transmission Parameters ◽  
Fitness Benefits

ABSTRACT The severity of human infection with pathogenic Escherichia coli depends on two major virulence determinants (eae and stx) that, respectively, produce intimin and Shiga toxin. In cattle, both may enhance colonization, but whether this increases fitness by enhancing cattle-to-cattle transmission in the field is unknown. In E. coli O157, the almost uniform presence of the virulence determinants in cattle isolates prevents comparative analysis. The availability to this study of extensive non-O157 E. coli data, with much greater diversity in carriage of virulence determinants, provides the opportunity to gain insight into their potential impact on transmission. Dynamic models were used to simulate expected prevalence distributions for serogroups O26 and O103. Transmission parameters were estimated by fitting model outputs to prevalence data from Scottish cattle using a Bayesian Markov chain Monte Carlo (MCMC) approach. Despite similar prevalence distributions for O26 and O103, their transmission dynamics were distinct. Serogroup O26 strains appear well adapted to the cattle host. The dynamics are characterized by a basic reproduction ratio (R 0) of >1 (allowing sustained cattle-to-cattle transmission), a relatively low transmission rate from environmental reservoirs, and substantial association with eae on transmission. The presence of stx 2 was associated with reduced transmission. In contrast, serogroup O103 appears better adapted to the noncattle environment, characterized by an R 0 value of <1 for plausible test sensitivities, a significantly higher transmission rate from noncattle sources than serogroup O26, and an absence of fitness benefits associated with the carriage of eae. Thus, the association of eae with enhanced transmission depends on the E. coli serogroup. Our results suggest that the capacity of E. coli strains to derive fitness benefits from virulence determinants influences the prevalence in the cattle population and the ecology and epidemiology of the host organism.

scholarly journals Genetic background affects epistatic interactions between two beneficial mutations

2013 ◽  
Vol 9 (1) ◽  
pp. 20120328 ◽  
Author(s):  
Yinhua Wang ◽  
Carolina Díaz Arenas ◽  
Daniel M. Stoebel ◽  
Tim F. Cooper
Keyword(s):  
Escherichia Coli ◽  
Genetic Background ◽  
General Pattern ◽  
Experimental Studies ◽  
Natural Isolate ◽  
Phenotypic Effect ◽  
Fitness Effect ◽  
Epistatic Interactions ◽  
Beneficial Mutations ◽  
E Coli

The phenotypic effect of mutations can depend on their genetic background, a phenomenon known as epistasis. Many experimental studies have found that epistasis is pervasive, and some indicate that it may follow a general pattern dependent on the fitness effect of the interacting mutations. These studies have, however, typically examined the effect of interactions between a small number of focal mutations in a single genetic background. Here, we extend this approach by considering how the interaction between two beneficial mutations that were isolated from a population of laboratory evolved Escherichia coli changes when they are added to divergent natural isolate strains of E. coli . We find that interactions between the focal mutations and the different genetic backgrounds are common. Moreover, the pair-wise interaction between the focal mutations also depended on their genetic background, being more negative in backgrounds with higher absolute fitness. Together, our results indicate the presence of interactions between focal mutations, but also caution that these interactions depend quantitatively on the wider genetic background.

scholarly journals Genetic Mutations That Drive Evolutionary Rescue to Lethal Temperature in Escherichia coli

2020 ◽  
Vol 12 (11) ◽  
pp. 2029-2044
Author(s):  
Tiffany N Batarseh ◽  
Shaun M Hug ◽  
Sarah N Batarseh ◽  
Brandon S Gaut
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Expression Patterns ◽  
Temperature Adaptation ◽  
Relative Fitness ◽  
Lethal Temperature ◽  
Adaptive Mutations ◽  
E Coli ◽  
Unstressed State ◽  
Evolutionary Rescue

Abstract Evolutionary rescue occurs when adaptation restores population growth against a lethal stressor. Here, we studied evolutionary rescue by conducting experiments with Escherichia coli at the lethal temperature of 43.0 °C, to determine the adaptive mutations that drive rescue and to investigate their effects on fitness and gene expression. From hundreds of populations, we observed that ∼9% were rescued by genetic adaptations. We sequenced 26 populations and identified 29 distinct mutations. Of these populations, 21 had a mutation in the hslVU or rpoBC operon, suggesting that mutations in either operon could drive rescue. We isolated seven strains of E. coli carrying a putative rescue mutation in either the hslVU or rpoBC operon to investigate the mutations’ effects. The single rescue mutations increased E. coli’s relative fitness by an average of 24% at 42.2 °C, but they decreased fitness by 3% at 37.0 °C, illustrating that antagonistic pleiotropy likely affected the establishment of rescue in our system. Gene expression analysis revealed only 40 genes were upregulated across all seven mutations, and these were enriched for functions in translational and flagellar production. As with previous experiments with high temperature adaptation, the rescue mutations tended to restore gene expression toward the unstressed state, but they also caused a higher proportion of novel gene expression patterns. Overall, we find that rescue is infrequent, that it is facilitated by a limited number of mutational targets, and that rescue mutations may have qualitatively different effects than mutations that arise from evolution to nonlethal stressors.

scholarly journals Invasiveness of Escherichia coli Is Associated with an IncFII Plasmid

Pathogens ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1645
Author(s):  
Lars Johannes Krall ◽  
Sabrina Klein ◽  
Sébastien Boutin ◽  
Chia Ching Wu ◽  
Aline Sähr ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bloodstream Infections ◽  
Intestinal Epithelial ◽  
Genetic Changes ◽  
E Coli ◽  
Underlying Mechanisms ◽  
Evolutionary Route ◽  
Invasion Assays

Escherichia coli is one of the most prevalent pathogens, causing a variety of infections including bloodstream infections. At the same time, it can be found as a commensal, being part of the intestinal microflora. While it is widely accepted that pathogenic strains can evolve from colonizing E. coli strains, the evolutionary route facilitating the commensal-to-pathogen transition is complex and remains not fully understood. Identification of the underlying mechanisms and genetic changes remains challenging. To investigate the factors involved in the transition from intestinal commensal to invasive E. coli causing bloodstream infections, we compared E. coli isolated from blood culture to isolates from the rectal flora of the same individuals by whole genome sequencing to identify clonally related strains and potentially relevant virulence factors. in vitro invasion assays using a Caco- 2 cell intestinal epithelial barrier model and a gut organoid model were performed to compare clonally related E. coli. The experiments revealed a correlation between the presence of an IncFII plasmid carrying hha and the degree of invasiveness. In summary, we provide evidence for the role of an IncFII plasmid in the transition of colonization to invasion in clinical E. coli isolates.

scholarly journals Aminoglycosides induce a bacterial senescent state that increases antibiotic tolerance in treatment-naïve cells

2021 ◽  
Author(s):  
Christian T. Meyer ◽  
Giancarlo N. Bruni ◽  
Ben Dodd ◽  
Joel M. Kralj
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Bacterial Species ◽  
Genetic Resistance ◽  
Membrane Integrity ◽  
Antibiotic Tolerance ◽  
Paracrine Signaling ◽  
E Coli ◽  
Evolutionary Innovation ◽  
Treatment Naïve

Bacterial evolution of antibiotic resistance is facilitated by non-genetic resistance that increases drug tolerance, buying time for evolutionary innovation. Escherichia coli treated with aminoglycosides permanently lose the ability to divide within four hours, yet we discovered a majority of cells maintain membrane integrity and metabolic activity greater than two days post treatment — a bacterial senescent-like state. These cells, which we term zombies, exhibit dynamic gene expression and metabolomic profiles, even after irreversible exit from the cell cycle. Our data reveal zombies upregulate the phage shock protein pathway to maintain membrane integrity. Remarkably, though unable to form new colonies, zombies increase the antibiotic tolerance of treatment-naïve cells, implying chemical communication. Chemical supplementation and genetic knockouts show that zombies communicate with treatment-naïve cells by secreting indole. In summary, our study revealed a bacterial senescent-like state, induced by aminoglycosides, that decreases the antibiotic susceptibility of multiple bacterial species. Thus, E. coli zombies utilize paracrine signaling to promote non-genetic antibiotic tolerance.

scholarly journals Differential Spectrum of Mutations That Activate the Escherichia coli bgl Operon in an rpoS Genetic Background

2002 ◽  
Vol 184 (14) ◽  
pp. 4033-4038 ◽  
Author(s):  
Sudha Moorthy ◽  
S. Mahadevan
Keyword(s):  
Escherichia Coli ◽  
Natural Populations ◽  
Structural Elements ◽  
Wild Type ◽  
Genetic Changes ◽  
E Coli ◽  
Activating Mutations ◽  
Major Class ◽  
Insertion Elements ◽  
Dna Insertion

ABSTRACT The bgl promoter is silent in wild-type Escherichia coli under standard laboratory conditions, and as a result, cells exhibit a β-glucoside-negative (Bgl−) phenotype. Silencing is brought about by negative elements that flank the promoter and include DNA structural elements and sequences that interact with the nucleoid-associated protein H-NS. Mutations that confer a Bgl+ phenotype arise spontaneously at a detectable frequency. Transposition of DNA insertion elements within the regulatory locus, bglR, constitutes the major class of activating mutations identified in laboratory cultures. The rpoS-encoded σS, the stationary-phase sigma factor, is involved in both physiological as well as genetic changes that occur in the cell under stationary-state conditions. In an attempt to see if the rpoS status of the cell influences the nature of the mutations that activate the bgl promoter, we analyzed spontaneously arising Bgl+ mutants in rpoS+ and rpoS genetic backgrounds. We show that the spectrum of activating mutations in rpoS cells is different from that in rpoS+ cells. Unlike rpoS+ cells, where insertions in bglR are the predominant activating mutations, mutations in hns make up the majority in rpoS cells. The physiological significance of these differences is discussed in the context of survival of natural populations of E. coli.

scholarly journals Adaptation of Escherichia coli ATCC 8739 to 11% NaCl

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Jian Ann How ◽  
Joshua Z. R. Lim ◽  
Desmond J. W. Goh ◽  
Wei Chuan Ng ◽  
Jack S. H. Oon ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Microbial Growth ◽  
Food Additive ◽  
Human Diet ◽  
Genetic Changes ◽  
E Coli ◽  
Gram Staining ◽  
Pcr Rflp ◽  
Dna Profiles ◽  
Kinetics Of

Escherichia coli (E. coli) is a nonhalophilic microbe and used to indicate faecal contamination. Salt (sodium chloride, NaCl) is a common food additive and is used in preservatives to encounter microbial growth. The effect of how E. coli interacts with the salt present in the human diet is unclear. Thus, it is important to investigate this relationship. In order to adapt and survive the changes in the environment, E. coli may undergo halophilization. In this study, we observed the genetic changes and growth kinetics of E. coli ATCC 8739 under 3%–11% NaCl over 80 passages. Our results suggest that E. coli adapted to 1% increase in NaCl every month with a successful adaptation to 11% NaCl. Gram staining and PCR/RFLP showed that the cultures are Gram negative and the DNA profiles of all 4 replicates to be similar, suggesting that the cultures had not been contaminated.

scholarly journals Bacteriocin diversity and the frequency of multiple bacteriocin production in Escherichia coli

Microbiology ◽  
2006 ◽  
Vol 152 (11) ◽  
pp. 3239-3244 ◽  
Author(s):  
David M. Gordon ◽  
Claire L. O'Brien
Keyword(s):  
Escherichia Coli ◽  
Mitomycin C ◽  
High Frequency ◽  
Cell Lysis ◽  
Bacteriocin Production ◽  
E Coli ◽  
Receptor Repertoire ◽  
Genetic Groups ◽  
Fitness Benefits ◽  
Colicin Ia

A collection of 266 faecal isolates of Escherichia coli from humans was assayed for the production of mitomycin C-inducible bacteriocins and screened using a PCR-based method for the presence of eleven colicins and seven microcins. Eight different colicins were detected and all seven microcins. Of the strains examined, 38 % produced a bacteriocin, 24 % produced a colicin and 20 % produced a microcin. Of the 102 bacteriocin-producing strains, 42 % produced one type of bacteriocin, 41 % produced two, 16 % produced three and one strain was found to produce four different bacteriocins. Strains producing more than one bacteriocin were more likely to be members of E. coli genetic group B2 and less likely to belong to genetic groups A or D. Several of the bacteriocins were found to co-occur in a strain more often than would be expected by chance: microcins H47 and M; colicin Ia and microcin V; colicins B and M; colicins E1 and M; colicins E1 and Ia. No bacteriocins released as a consequence of cell lysis were found to co-associate more often than expected by chance. Three non-mutually exclusive hypotheses are presented that might explain the high frequency of multiple bacteriocin production in E. coli strains: (1) expanded killing range, (2) expanded receptor repertoire and (3) fitness benefits in different environments.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

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