scholarly journals Variation in Resistance to High Hydrostatic Pressure andrpoS Heterogeneity in Natural Isolates ofEscherichia coli O157:H7

2001 ◽  
Vol 67 (10) ◽  
pp. 4901-4907 ◽  
Author(s):  
Marianne Robey ◽  
Amparo Benito ◽  
Roger H. Hutson ◽  
Cristina Pascual ◽  
Simon F. Park ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
Stationary Phase ◽  
Sigma Factor ◽  
High Hydrostatic Pressure ◽  
E Coli ◽  
Commensal Strain ◽  
Natural Isolates ◽  
Pressure Resistance ◽  
Sigma Factor Rpos

ABSTRACT Several natural isolates of Escherichia coliO157:H7 have previously been shown to exhibit stationary-phase-dependent variation in their resistance to inactivation by high hydrostatic pressure. In this report we demonstrate that loss of the stationary-phase-inducible sigma factor RpoS resulted in decreased resistance to pressure inE. coli O157:H7 and in a commensal strain. Furthermore, variation in the RpoS activity of the natural isolates of O157:H7 correlated with the pressure resistance of those strains. Heterogeneity was noted in the rpoS alleles of the natural isolates that may explain the differences in RpoS activity. These results are consistent with a role for rpoS in mediating resistance to high hydrostatic pressure in E. coliO157:H7.

scholarly journals Induction of Shiga Toxin-Converting Prophage in Escherichia coli by High Hydrostatic Pressure

2005 ◽  
Vol 71 (3) ◽  
pp. 1155-1162 ◽  
Author(s):  
Abram Aertsen ◽  
David Faster ◽  
Chris W. Michiels
Keyword(s):  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
Shiga Toxin ◽  
High Hydrostatic Pressure ◽  
Sos Response ◽  
Resistant Mutant ◽  
Food Preservation ◽  
Bacterial Survival ◽  
E Coli ◽  
Pressure Resistance

ABSTRACT Since high hydrostatic pressure is becoming increasingly important in modern food preservation, its potential effects on microorganisms need to be thoroughly investigated. In this context, mild pressures (<200 MPa) have recently been shown to induce an SOS response in Escherichia coli MG1655. Due to this response, we observed a RecA- and LexA-dependent induction of lambda prophage upon treating E. coli lysogens with sublethal pressures. In this report, we extend this observation to lambdoid Shiga toxin (Stx)-converting bacteriophages in MG1655, which constitute an important virulence trait in Stx-producing E. coli strains (STEC). The window of pressures capable of inducing Stx phages correlated well with the window of bacterial survival. When pressure treatments were conducted in whole milk, which is known to promote bacterial survival, Stx phage induction could be observed at up to 250 MPa in E. coli MG1655 and at up to 300 MPa in a pressure-resistant mutant of this strain. In addition, we found that the intrinsic pressure resistance of two types of Stx phages was very different, with one type surviving relatively well treatments of up to 400 MPa for 15 min at 20°C. Interestingly, and in contrast to UV irradiation or mitomycin C treatment, pressure was not able to induce Stx prophage or an SOS response in several natural Stx-producing STEC isolates.

scholarly journals Identification of novel genes involved in high hydrostatic pressure resistance of Escherichia coli

2019 ◽  
Vol 78 ◽  
pp. 171-178 ◽  
Author(s):  
Elisa Gayán ◽  
Nele Rutten ◽  
Jan Van Impe ◽  
Chris W. Michiels ◽  
Abram Aertsen
Keyword(s):  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Novel Genes ◽  
Pressure Resistance

scholarly journals The genome-wide transcriptional response to varying RpoS levels inEscherichia coliK-12

2016 ◽  
Author(s):  
Garrett T. Wong ◽  
Richard P. Bonocora ◽  
Alicia N. Schep ◽  
Suzannah M. Beeler ◽  
Anna J. Lee Fong ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Stress Responses ◽  
Sigma Factor ◽  
Core Promoter ◽  
Transcriptional Response ◽  
Transcriptional Responses ◽  
Cellular Processes ◽  
Functional Classes ◽  
Sigma Factor Rpos

AbstractThe alternative sigma factor RpoS is a central regulator of a many stress responses inEscherichia coli.The level of functional RpoS differs depending on the stress. The effect of these differing concentrations of RpoS on global transcriptional responses remains unclear. We investigated the effect of RpoS concentration on the transcriptome during stationary phase in rich media. We show that 23% of genes in theE. coligenome are regulated by RpoS level, and we identify many RpoS-transcribed genes and promoters. We observe three distinct classes of response to RpoS by genes in the regulon: genes whose expression changes linearly with increasing RpoS level, genes whose expression changes dramatically with the production of only a little RpoS (“sensitive” genes), and genes whose expression changes very little with the production of a little RpoS (“insensitive”). We show that sequences outside the core promoter region determine whether a RpoS-regulated gene in sensitive or insensitive. Moreover, we show that sensitive and insensitive genes are enriched for specific functional classes, and that the sensitivity of a gene to RpoS corresponds to the timing of induction as cells enter stationary phase. Thus, promoter sensitivity to RpoS is a mechanism to coordinate specific cellular processes with growth phase, and may also contribute to the diversity of stress responses directed by RpoS.ImportanceThe sigma factor RpoS is a global regulator that controls the response to many stresses inEscherichia coli.Different stresses result in different levels of RpoS production, but the consequences of this variation are unknown. We describe how changing the level of RpoS does not influence all RpoS-regulated genes equally. The cause of this variation is likely the action of transcription factors that bind the promoters of the genes. We show that the sensitivity of a gene to RpoS levels explains the timing of expression as cells enter stationary phase, and that genes with different RpoS sensitivities are enriched for specific functional groups. Thus, promoter sensitivity to RpoS is a mechanism to coordinate specific cellular processes in response to stresses.

Stationary-Phase Acid Resistance and Injury of Recent Bovine Escherichia coli O157 and non-O157 Biotype I Escherichia coli Isolates†

2004 ◽  
Vol 67 (3) ◽  
pp. 583-590 ◽  
Author(s):  
E. D. BERRY ◽  
G. A. BARKOCY-GALLAGHER ◽  
G. R. SIRAGUSA
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Acid Resistance ◽  
Low Ph ◽  
Acid Adaptation ◽  
E Coli ◽  
Log Reduction ◽  
Natural Isolates ◽  
Acidic Conditions ◽  
Ph Challenge

Stationary-phase acid resistance and the induction of acid resistance were assessed for recent bovine carcass isolates of Escherichia coli, including 39 serotype O157 strains and 20 non-O157 strains. When grown to stationary phase in the absence of glucose and without prior acid exposure, there was a range of responses to a pH challenge of 6 h at pH 2.5. However, populations of 53 of the 59 E. coli isolates examined were reduced by less than 2.00 log CFU/ml, and populations of 24 of these isolates were reduced by less than 1.00 log CFU/ml. In contrast, there was little variation in population reductions when the E. coli were grown with glucose and preadapted to acidic conditions. With few exceptions, acid adaptation improved survival to the acid challenge, with 57 of the 59 isolates exhibiting a log reduction of less than 0.50. Differences in acid resistance or the ability to adapt to acidic conditions between E. coli O157:H7 and non-O157 commensal E. coli were not observed. However, we did find that the E. coli O157 were disposed to greater acid injury after the low pH challenge than the non-O157 E. coli, both for cells that were and were not adapted to acidic conditions before the challenge. The enhancement of low pH survival after acid adaptation that was seen among these recent natural isolates of E. coli O157 further supports the idea that the previous environment of this pathogen should be a consideration when designing microbial safety strategies for foods preserved by low pH and acid.

Loss of cAMP/CRP regulation confers extreme high hydrostatic pressure resistance in Escherichia coli O157:H7

2013 ◽  
Vol 166 (1) ◽  
pp. 65-71 ◽  
Author(s):  
Dietrich Vanlint ◽  
Brecht J.Y. Pype ◽  
Nele Rutten ◽  
Kristof G.A. Vanoirbeek ◽  
Chris W. Michiels ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Escherichia Coli O157 ◽  
Pressure Resistance

scholarly journals Experimental Evolution ofEscherichia coliK-12 at High pH and with RpoS Induction

2018 ◽  
Vol 84 (15) ◽  
Author(s):  
Issam Hamdallah ◽  
Nadia Torok ◽  
Katarina M. Bischof ◽  
Nadim Majdalani ◽  
Sriya Chadalavada ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Experimental Evolution ◽  
Sigma Factor ◽  
Point Mutations ◽  
Envelope Proteins ◽  
Content Type ◽  
High Ph ◽  
K 12 ◽  
Sigma Factor Rpos

ABSTRACTExperimental evolution ofEscherichia coliK-12 W3110 by serial dilutions for 2,200 generations at high pH extended the range of sustained growth from pH 9.0 to pH 9.3. pH 9.3-adapted isolates showed mutations in DNA-binding regulators and envelope proteins. One population showed an IS1knockout ofphoB(encoding the positive regulator of the phosphate regulon). AphoB::kanRknockout increased growth at high pH.phoBmutants are known to increase production of fermentation acids, which could enhance fitness at high pH. Mutations inpcnB[poly(A) polymerase] also increased growth at high pH. Three out of four populations showed deletions oftorI, an inhibitor of TorR, which activates expression oftorCAD(trimethylamineN-oxide respiration) at high pH. All populations showed point mutations affecting the stationary-phase sigma factor RpoS, either in the coding gene or in genes for regulators of RpoS expression. RpoS is required for survival at extremely high pH. In our microplate assay,rpoSdeletion slightly decreased growth at pH 9.1. RpoS protein accumulated faster at pH 9 than at pH 7. The RpoS accumulation at high pH required the presence of one or more antiadaptors that block degradation (IraM, IraD, and IraP). Other genes with mutations after high-pH evolution encode regulators, such as those encoded byyobG(mgrB) (PhoPQ regulator),rpoN(nitrogen starvation sigma factor),malI, andpurR, as well as envelope proteins, such as those encoded byompTandyahO. Overall,E. colievolution at high pH selects for mutations in key transcriptional regulators, includingphoBand the stationary-phase sigma factor RpoS.IMPORTANCEEscherichia coliin its native habitat encounters high-pH stress such as that of pancreatic secretions. Experimental evolution over 2,000 generations showed selection for mutations in regulatory factors, such as deletion of the phosphate regulator PhoB and mutations that alter the function of the global stress regulator RpoS. RpoS is induced at high pH via multiple mechanisms.

scholarly journals A Mutant RNA Polymerase Activates the General Stress Response, Enabling Escherichia coli Adaptation to Late Prolonged Stationary Phase

mSphere ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Pabitra Nandy ◽  
Savita Chib ◽  
Aswin Seshasayee
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Stationary Phase ◽  
Sigma Factor ◽  
Slow Growth ◽  
Content Type ◽  
General Stress Response ◽  
E Coli ◽  
General Stress ◽  
Small Colony

ABSTRACT Escherichia coli populations undergo repeated replacement of parental genotypes with fitter variants deep in stationary phase. We isolated one such variant, which emerged after 3 weeks of maintaining an E. coli K-12 population in stationary phase. This variant displayed a small colony phenotype and slow growth and was able to outcompete its ancestor over a narrow time window in stationary phase. The variant also shows tolerance to beta-lactam antibiotics, though not previously exposed to the antibiotic. We show that an RpoC(A494V) mutation confers the slow growth and small colony phenotype on this variant. The ability of this mutation to confer a growth advantage in stationary phase depends on the availability of the stationary-phase sigma factor σS. The RpoC(A494V) mutation upregulates the σS regulon. As shown over 20 years ago, early in prolonged stationary phase, σS attenuation, but not complete loss of activity, confers a fitness advantage. Our study shows that later mutations enhance σS activity, either by mutating the gene for σS directly or via mutations such as RpoC(A494V). The balance between the activities of the housekeeping major sigma factor and σS sets up a trade-off between growth and stress tolerance, which is tuned repeatedly during prolonged stationary phase. IMPORTANCE An important general mechanism of a bacterium’s adaptation to its environment involves adjusting the balance between growing fast and tolerating stresses. One paradigm where this plays out is in prolonged stationary phase: early studies showed that attenuation, but not complete elimination, of the general stress response enables early adaptation of the bacterium E. coli to the conditions established about 10 days into stationary phase. We show here that this balance is not static and that it is tilted back in favor of the general stress response about 2 weeks later. This can be established by direct mutations in the master regulator of the general stress response or by mutations in the core RNA polymerase enzyme itself. These conditions can support the development of antibiotic tolerance although the bacterium is not exposed to the antibiotic. Further exploration of the growth-stress balance over the course of stationary phase will necessarily require a deeper understanding of the events in the extracellular milieu.

scholarly journals Heat Shock Protein-Mediated Resistance to High Hydrostatic Pressure in Escherichia coli

2004 ◽  
Vol 70 (5) ◽  
pp. 2660-2666 ◽  
Author(s):  
Abram Aertsen ◽  
Kristof Vanoirbeek ◽  
Philipp De Spiegeleer ◽  
Jan Sermon ◽  
Kristel Hauben ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Pressure ◽  
Hydrostatic Pressure ◽  
Heat Shock ◽  
Heat Shock Proteins ◽  
High Hydrostatic Pressure ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
E Coli ◽  
Shock Proteins

ABSTRACT A random library of Escherichia coli MG1655 genomic fragments fused to a promoterless green fluorescent protein (GFP) gene was constructed and screened by differential fluorescence induction for promoters that are induced after exposure to a sublethal high hydrostatic pressure stress. This screening yielded three promoters of genes belonging to the heat shock regulon (dnaK, lon, clpPX), suggesting a role for heat shock proteins in protection against, and/or repair of, damage caused by high pressure. Several further observations provide additional support for this hypothesis: (i) the expression of rpoH, encoding the heat shock-specific sigma factor σ32, was also induced by high pressure; (ii) heat shock rendered E. coli significantly more resistant to subsequent high-pressure inactivation, and this heat shock-induced pressure resistance followed the same time course as the induction of heat shock genes; (iii) basal expression levels of GFP from heat shock promoters, and expression of several heat shock proteins as determined by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins extracted from pulse-labeled cells, was increased in three previously isolated pressure-resistant mutants of E. coli compared to wild-type levels.

Combined Effect of High Hydrostatic Pressure and Nisin on Loss of Viability, Membrane Damage and Release of Intracellular Contents of Bacillus subtilis and Escherichia coli

2010 ◽  
Vol 6 (5) ◽  
Author(s):  
Wei-Min Qi ◽  
Ping Qian ◽  
Jian-Yong Yu ◽  
Chi-Yu Zhang ◽  
Xiao Chen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Hydrostatic Pressure ◽  
Synergistic Effect ◽  
High Hydrostatic Pressure ◽  
Cell Envelope ◽  
Membrane Damage ◽  
Combined Effect ◽  
Gram Negative Bacteria ◽  
E Coli

Bacillus subtilis and Escherichia coli were chosen to investigate the combined effect of high hydrostatic pressure (HHP) and Nisin on loss of viability, membrane damage and release of intracellular contents of microorganisms. The results showed that the combination of 200 IU/mL Nisin and HHP exhibited a synergistic effect over 2 log on the inactivation of B. subtilis at pressure 300 MPa. The similar synergistic effect was observed on the membrane damage and release of intracellular contents of B. subtilis. The Nisin alone had no effect against E. coli, which belongs to gram negative bacteria. However, at pressure 300 MPa, Nisin caused the membrane damage from 55% to 80%. The synergistic effect of Nisin and HHP on loss of viability, membrane damage and release of intracellular contents of E. coli were also illustrated when the HHP pressure exceeded 300 MPa as the consequence of the serious changes produced by HHP at higher pressure in the cell envelope. It allows the entry of Nisin molecules to cell membrane.

scholarly journals Genome-Wide Transcriptional Response to Varying RpoS Levels in Escherichia coli K-12

2017 ◽  
Vol 199 (7) ◽  
Author(s):  
Garrett T. Wong ◽  
Richard P. Bonocora ◽  
Alicia N. Schep ◽  
Suzannah M. Beeler ◽  
Anna J. Lee Fong ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Stress Responses ◽  
Sigma Factor ◽  
Core Promoter ◽  
Transcriptional Responses ◽  
Content Type ◽  
Cellular Processes ◽  
K 12 ◽  
Sigma Factor Rpos

ABSTRACT The alternative sigma factor RpoS is a central regulator of many stress responses in Escherichia coli. The level of functional RpoS differs depending on the stress. The effect of these differing concentrations of RpoS on global transcriptional responses remains unclear. We investigated the effect of RpoS concentration on the transcriptome during stationary phase in rich media. We found that 23% of genes in the E. coli genome are regulated by RpoS, and we identified many RpoS-transcribed genes and promoters. We observed three distinct classes of response to RpoS by genes in the regulon: genes whose expression changes linearly with increasing RpoS level, genes whose expression changes dramatically with the production of only a little RpoS (“sensitive” genes), and genes whose expression changes very little with the production of a little RpoS (“insensitive”). We show that sequences outside the core promoter region determine whether an RpoS-regulated gene is sensitive or insensitive. Moreover, we show that sensitive and insensitive genes are enriched for specific functional classes and that the sensitivity of a gene to RpoS corresponds to the timing of induction as cells enter stationary phase. Thus, promoter sensitivity to RpoS is a mechanism to coordinate specific cellular processes with growth phase and may also contribute to the diversity of stress responses directed by RpoS. IMPORTANCE The sigma factor RpoS is a global regulator that controls the response to many stresses in Escherichia coli. Different stresses result in different levels of RpoS production, but the consequences of this variation are unknown. We describe how changing the level of RpoS does not influence all RpoS-regulated genes equally. The cause of this variation is likely the action of transcription factors that bind the promoters of the genes. We show that the sensitivity of a gene to RpoS levels explains the timing of expression as cells enter stationary phase and that genes with different RpoS sensitivities are enriched for specific functional groups. Thus, promoter sensitivity to RpoS is a mechanism that coordinates specific cellular processes in response to stresses.

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