Survival ofEscherichia coliexposed to visible light in seawater: analysis ofrpoS-dependent effects

1997 ◽  
Vol 43 (11) ◽  
pp. 1036-1043 ◽  
Author(s):  
M. Gourmelon ◽  
M. Pommepuy ◽  
D. Touati ◽  
M. Cormier
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Visible Light ◽  
Adaptive Response ◽  
Regulatory Gene ◽  
Exponential Phase ◽  
E Coli ◽  
Rpos Mutant ◽  
Increased Sensitivity ◽  
Key Words Escherichia Coli

We investigated the effect of visible light on Escherichia coli in seawater microcosms. Escherichia coli lost its ability to form colonies in marine environments when exposed to artificial continuous visible light. Survival of illuminated bacteria during the stationary phase was drastically reduced in the absence of the σsfactor (RpoS or KatF) that regulates numerous genes induced in this phase. In the stationary phase, double catalase mutants katE katG and mutants defective in the protein Dps (both catalase and Dps are involved in resistance to hydrogen peroxide (H2O2)), were more sensitive to light. In the exponential phase, a mutation in oxyR, the regulatory gene of the adaptive response to H2O2, increased sensitivity to light, further suggesting that deleterious effects might be associated with H2O2production. However, in the stationary phase, the katE katG dps mutant was considerably more resistant to visible light than the rpoS mutant, suggesting rpoS-dependent protection against deleterious effects other than those related to H2O2. The deleterious action of visible light was less important when the salinity decreased. In freshwater, rpoS and katE katG dps mutants did not show a drastic difference in sensitivity to light suggesting that osmolarity sensitizes E. coli to those deleterious effects of visible light that are unrelated to H2O2.Key words: Escherichia coli, stationary phase, RpoS, visible light, seawater.

Mannose-Binding Activity of Escherichia coli: a Determinant of Attachment and Ingestion of the Bacteria by Macrophages

1980 ◽  
Vol 29 (2) ◽  
pp. 417-424
Author(s):  
Zvi Bar-Shavit ◽  
Rachel Goldman ◽  
Itzhak Ofek ◽  
Nathan Sharon ◽  
David Mirelman
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Pathogenic Bacteria ◽  
Binding Activity ◽  
Exponential Phase ◽  
Restrictive Temperature ◽  
Filamentous Bacteria ◽  
Phagocytic Cells ◽  
E Coli ◽  
Mannose Binding

Recently, it was suggested that a mannose-specific lectin on the bacterial cell surface is responsible for the recognition by phagocytic cells of certain nonopsonized Escherichia coli strains. In this study we assessed the interaction of two strains of E. coli at different phases of growth with a monolayer of mouse peritoneal macrophages and developed a direct method with [ 14 C]mannan to quantitate the bacterial mannose-binding activity. Normal-sized bacteria were obtained from logarithmic and stationary phases of growth. Nonseptated filamentous cells were formed by growing the organisms in the presence of cephalexin or at a restrictive temperature. Attachment to macrophages of all bacterial forms was inhibited by methyl α- d -mannoside and mannan but not by other sugars tested. The attachment of stationary phase and filamentous bacteria to macrophages, as well as their mannose-binding activity, was similar, whereas in the exponential-phase bacteria they were markedly reduced. The results show a linear relation between the two parameters ( R = 0.98, P < 0.001). The internalization of the filamentous cells attached to macrophages during 45 min of incubation was much less efficient (20%) compared to that of exponential-phase, stationary-phase, or antibody-coated filamentous bacteria (90%). The results indicate that the mannose-binding activity of E. coli determines the recognition of the organisms by phagocytes. They further suggest that administration of β-lactam antibiotics may impair elimination of certain pathogenic bacteria by inducing the formation of filaments which are inefficiently internalized by the host's phagocytic cells.

Bacteriophage infection and multiplication occur inPseudomonas aeruginosastarved for 5 years

1997 ◽  
Vol 43 (12) ◽  
pp. 1157-1163 ◽  
Author(s):  
Holly S. Schrader ◽  
John O. Schrader ◽  
Jeremy J. Walker ◽  
Thomas A. Wolf ◽  
Kenneth W. Nickerson ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Stationary Phase ◽  
Burst Size ◽  
Exponential Phase ◽  
Bacterial Mortality ◽  
E Coli ◽  
Bacteriophage Infection

Bacteriophages specific for Pseudomonas aeruginosa and Escherichia coli were examined for their ability to multiply in stationary phase hosts. Four out of five bacteriophages tested, including E. coli bacteriophage T7M, were able to multiply in stationary phase hosts. The bacteriophage ACQ had a mean burst size of approximately 1000 in exponential phase P. aeruginosa hosts and 102 in starved hosts, with corresponding latent periods that increased from 65 to 210 min. The bacteriophage UT1 had a mean burst size of approximately 211 in exponential phase P. aeruginosa hosts and 11 in starved hosts, with latent periods that increased from a mean of 90 min in exponential phase hosts to 165 min in starved hosts. Bacteriophage multiplication occurred whether or not the hosts had entered stationary phase, either because the cultures had been incubated for 24 h or were starved. Significantly, bacteriophage multiplication occurred in P. aeruginosa, which had been starved for periods of 24 h, several weeks, or 5 years. Only one P. aeruginosa virus, BLB, was found to be incapable of multiplication in stationary phase hosts. These results reveal that starvation does not offer bacterial hosts refuge from bacteriophage infection and suggest that bacteriophages will be responsible for significant bacterial mortality in most natural ecosystems.Key words: bacteriophage multiplication, stationary phase, starvation.

Further investigation of the mechanism of Vitreoscilla hemoglobin (VHb) protection from oxidative stress in Escherichia coli

Biologia ◽  
2011 ◽  
Vol 66 (5) ◽  
Author(s):  
Meltem Akbas ◽  
Tugrul Doruk ◽  
Serhat Ozdemir ◽  
Benjamin Stark
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Stationary Phase ◽  
Exponential Phase ◽  
Vitreoscilla Hemoglobin ◽  
Sod Activity ◽  
E Coli ◽  
Hydrogen Peroxide Treatment

AbstractIn Escherichia coli, Vitreoscilla hemoglobin (VHb) protects against oxidative stress, perhaps, in part, by oxidizing OxyR. Here this protection, specifically VHb-associated effects on superoxide dismutase (SOD) and catalase levels, was examined. Exponential or stationary phase cultures of SOD+ or SOD− E. coli strains with or without VHb and oxyR antisense were treated with 2 mM hydrogen peroxide without sublethal peroxide induction, and compared to untreated control cultures. The hydrogen peroxide treatment was toxic to both SOD+ and SOD− cells, but much more to SOD− cells; expression of VHb in SOD+ strains enhanced this toxicity. In contrast, the presence of VHb was generally associated in the SOD+ background with a modest increase in SOD activity that was not greatly affected by oxyR antisense or peroxide treatment. In both SOD+ and SOD− backgrounds, VHb was associated with higher catalase activity both in the presence and absence of peroxide. Contrary to its stimulatory effects in stationary phase, in exponential phase oxyR antisense generally decreased VHb levels.

Antecedent Oxygen Growth Conditions and Recovery of Heat-Stressed Escherichia coli1

1991 ◽  
Vol 54 (2) ◽  
pp. 90-93 ◽  
Author(s):  
CAROLINE E. O'NEILL ◽  
GARY K. BISSONNETTE
Keyword(s):  
Escherichia Coli ◽  
Heat Stress ◽  
Thermal Stress ◽  
Stationary Phase ◽  
Physiological State ◽  
Growth Conditions ◽  
Exponential Phase ◽  
Physiological Age ◽  
E Coli

Four strains of Escherichia coli were examined for response to heat stress (60°C) as a function of physiological age and antecedent oxygen growth conditions. Exponential phase cells were more susceptible to heat than cells grown to the stationary phase. Anaerobically grown, exponential phase cells were more susceptible to thermal stress than were cells grown to a similar physiological state but under aerobic conditions. In the case of stationary phase cells, differences in response to heat stress as related to prior oxygen growth conditions were equivocal. Repair characteristics of thermally injured cells were also examined. Cells grown anaerobically prior to heat stress required 1.5 h longer than their aerobically grown counterparts to complete repair. These findings suggest that antecedent oxygen growth conditions influence the response of E. coli to thermal stress and perhaps, more generally, that persistence of environmentally stressed enteric microorganisms must be considered in relation to prior oxygen growth conditions in vivo.

scholarly journals Importance of RpoS and Dps in Survival of Exposure of Both Exponential- and Stationary-Phase Escherichia coliCells to the Electrophile N-Ethylmaleimide

1998 ◽  
Vol 180 (5) ◽  
pp. 1030-1036 ◽  
Author(s):  
G. P. Ferguson ◽  
R. I. Creighton ◽  
Y. Nikolaev ◽  
I. R. Booth
Keyword(s):  
Stationary Phase ◽  
Dna Binding Protein ◽  
Exponential Phase ◽  
Protective Mechanisms ◽  
E Coli ◽  
Enhanced Sensitivity ◽  
Enhanced Resistance ◽  
Quadruple Mutant ◽  
Increased Sensitivity ◽  
Protective Systems

ABSTRACT The mechanisms by which Escherichia coli cells survive exposure to the toxic electrophile N-ethylmaleimide (NEM) have been investigated. Stationary-phase E. coli cells were more resistant to NEM than exponential-phase cells. The KefB and KefC systems were found to play an important role in protecting both exponential- and stationary-phase cells against NEM. Additionally, RpoS and the DNA-binding protein Dps aided the survival of both exponential- and stationary-phase cells against NEM. Double mutants lacking both RpoS and Dps and triple mutants deficient in KefB and KefC and either RpoS or Dps had an increased sensitivity to NEM in both exponential- and stationary-phase cells compared to mutants missing only one of these protective mechanisms. Stationary- and exponential-phase cells of a quadruple mutant lacking all four protective systems displayed even greater sensitivity to NEM. These results indicated that protection by the KefB and KefC systems, RpoS and Dps can each occur independently of the other systems. Alterations in the level of RpoS in exponentially growing cells correlated with the degree of NEM sensitivity. Decreasing the level of RpoS by enriching the growth medium enhanced sensitivity to NEM, whereas a mutant lacking the ClpP protease accumulated RpoS and gained high levels of resistance to NEM. A slower-growing E. coli strain was also found to accumulate RpoS and had enhanced resistance to NEM. These data emphasize the multiplicity of pathways involved in protecting E. coli cells against NEM.

scholarly journals Role of rpoS in the regulation of glyoxalase III in Escherichia coli.

2004 ◽  
Vol 51 (3) ◽  
pp. 857-860 ◽  
Author(s):  
Ludmil Benov ◽  
Fatima Sequeira ◽  
Anees F Beema
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Enteric Bacteria ◽  
Glyoxalase I ◽  
Aldehyde Reductase ◽  
E Coli ◽  
Rpos Mutant ◽  
Phosphorylated Sugars ◽  
Glyoxalase Iii

Methylglyoxal is an endogenous electrophile produced in Escherichia coli by the enzyme methylglyoxal synthase to limit the accumulation of phosphorylated sugars. In enteric bacteria methylglyoxal is detoxified by the glutathione-dependent glyoxalase I/II system, by glyoxalase III, and by aldehyde reductase and alcohol dehydrogenase. Here we demonstrate that glyoxalase III is a stationary-phase enzyme. Its activity reached a maximum at the entry into the stationary phase and remained high for at least 20 h. An rpoS- mutant displayed normal glyoxalase I and II activities but was unable to induce glyoxalase III in stationary phase. It thus appears that glyoxalase III is regulated by rpoS and might be important for survival of non-growing E. coli cultures.

scholarly journals The l-Isoaspartyl Protein Repair Methyltransferase Enhances Survival of Aging Escherichia coli Subjected to Secondary Environmental Stresses

1998 ◽  
Vol 180 (10) ◽  
pp. 2623-2629 ◽  
Author(s):  
Jonathan E. Visick ◽  
Hui Cai ◽  
Steven Clarke
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Protein Denaturation ◽  
Environmental Stresses ◽  
Protein Repair ◽  
Repeated Heating ◽  
E Coli ◽  
Competitive Disadvantage ◽  
Biological World

ABSTRACT Like its homologs throughout the biological world, thel-isoaspartyl protein repair methyltransferase ofEscherichia coli, encoded by the pcm gene, can convert abnormal l-isoaspartyl residues in proteins (which form spontaneously from asparaginyl or aspartyl residues) to normal aspartyl residues. Mutations in pcm were reported to greatly reduce survival in stationary phase and when cells were subjected to heat or osmotic stresses (C. Li and S. Clarke, Proc. Natl. Acad. Sci. USA 89:9885–9889, 1992). However, we subsequently demonstrated that those strains had a secondary mutation inrpoS, which encodes a stationary-phase-specific sigma factor (J. E. Visick and S. Clarke, J. Bacteriol. 179:4158–4163, 1997). We now show that the rpoS mutation, resulting in a 90% decrease in HPII catalase activity, can account for the previously observed phenotypes. We further demonstrate that a new pcmmutant lacks these phenotypes. Interestingly, the newly constructedpcm mutant, when maintained in stationary phase for extended periods, is susceptible to environmental stresses, including exposure to methanol, oxygen radical generation by paraquat, high salt concentrations, and repeated heating to 42°C. The pcmmutation also results in a competitive disadvantage in stationary-phase cells. All of these phenotypes can be complemented by a functionalpcm gene integrated elsewhere in the chromosome. These data suggest that protein denaturation and isoaspartyl formation may act synergistically to the detriment of aging E. coli and that the repair methyltransferase can play a role in limiting the accumulation of the potentially disruptive isoaspartyl residues in vivo.

scholarly journals Studies on deoxyribonucleic acid-dependent ribonucleic acid polymerase from Escherichia coli. Variations of the enzyme activity during growth

1972 ◽  
Vol 129 (2) ◽  
pp. 291-299 ◽  
Author(s):  
K. A. Abraham ◽  
K. J. Andersen ◽  
A. Rognes
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Stationary Phases ◽  
Bacteriophage T4 ◽  
Polymerase Activity ◽  
Exponential Phase ◽  
Enzyme Preparations ◽  
Rna Polymerase Activity ◽  
Enzyme Molecules ◽  
Cellular Dna

1. RNA polymerase activity of Escherichia coli extracts prepared from cells in exponential and stationary phases of growth, when measured in the presence and absence of external template, showed significant qualitative differences. 2. In both extracts, polymerase activity was higher when assayed with external template, suggesting the presence of a pool of enzyme not bound to cellular DNA. 3. In the crude extract, the fraction of enzyme bound to cellular DNA is higher during the exponential phase of growth. 4. A method is described for the purification of enzyme molecules not tightly bound to cellular DNA from exponential- and stationary-phase cultures. 5. Purified enzyme preparations showed differences in template requirement and subunit composition. 6. On phosphocellulose chromatography of stationary-phase enzyme, a major portion of polymerase activity eluted from the column with 0.25m-KCl. In the case of exponential-phase enzyme, polymerase activity eluted from a phosphocellulose column mainly with 0.35m-KCl. 7. Enzyme assays done with excess of bacteriophage T4 DNA showed a strong inhibition of stationary-phase enzyme by this template. The exponential-phase enzyme was only slightly inhibited by excess of bacteriophage T4 DNA.

Quantitative profiling and dynamics of mRNA modifications in Escherichia coli

2021 ◽  
Author(s):  
Dimitar Plamenov Petrov ◽  
Steffen Kaiser ◽  
Stefanie Kaiser ◽  
Kirsten Jung
Keyword(s):  
Mass Spectrometry ◽  
Escherichia Coli ◽  
Stationary Phase ◽  
Exponential Growth ◽  
Gel Electrophoresis ◽  
E Coli ◽  
Physiological Processes ◽  
Mrna Methylation ◽  
Important Regulator ◽  
Quantitative Profiling

mRNA methylation is an important regulator of many physiological processes in eukaryotes but has not been studied in depth in prokaryotes. In contrast to the large number of eukaryotic mRNA modifications that have been described, N6-methyladenosine (m6A) is the only modification of bacterial mRNA identified to date. Here, we used a gel electrophoresis-based RNA separation method and quantitatively analyzed the mRNA-specific modification profile of Escherichia coli using mass spectrometry. In addition to m6A, we provide evidence for the presence of 7-methylguanosine (m7G), and we found first hints for 5-methylcytidine (m5C), N6,N6-dimethyladenosine (m6,6A), 1-methylguanosine (m1G), 5-methyluridine (m5U), and pseudouridine (Ψ) in the mRNA of E. coli, which implies that E. coli has a complex mRNA modification pattern. Furthermore, we observed changes in the abundance of some mRNA modifications during the transition of E. coli from the exponential growth to the stationary phase as well as upon exposure to stress. This study reveals a previously underestimated level of regulation between transcription and translation in bacteria.

scholarly journals Biophysical Properties of Escherichia coli Cytoplasm in Stationary Phase by Superresolution Fluorescence Microscopy

mBio ◽  
2020 ◽  
Vol 11 (3) ◽  
Author(s):  
Yanyu Zhu ◽  
Mainak Mustafi ◽  
James C. Weisshaar
Keyword(s):  
Escherichia Coli ◽  
Fluorescence Microscopy ◽  
Rna Polymerase ◽  
Stationary Phase ◽  
Exponential Growth ◽  
Mean Square Displacement ◽  
Quiescent State ◽  
Chromosomal Dna ◽  
Content Type ◽  
E Coli

ABSTRACT In nature, bacteria must survive long periods of nutrient deprivation while maintaining the ability to recover and grow when conditions improve. This quiescent state is called stationary phase. The biochemistry of Escherichia coli in stationary phase is reasonably well understood. Much less is known about the biophysical state of the cytoplasm. Earlier studies of harvested nucleoids concluded that the stationary-phase nucleoid is “compacted” or “supercompacted,” and there are suggestions that the cytoplasm is “glass-like.” Nevertheless, stationary-phase bacteria support active transcription and translation. Here, we present results of a quantitative superresolution fluorescence study comparing the spatial distributions and diffusive properties of key components of the transcription-translation machinery in intact E. coli cells that were either maintained in 2-day stationary phase or undergoing moderately fast exponential growth. Stationary-phase cells are shorter and exhibit strong heterogeneity in cell length, nucleoid volume, and biopolymer diffusive properties. As in exponential growth, the nucleoid and ribosomes are strongly segregated. The chromosomal DNA is locally more rigid in stationary phase. The population-weighted average of diffusion coefficients estimated from mean-square displacement plots is 2-fold higher in stationary phase for both RNA polymerase (RNAP) and ribosomal species. The average DNA density is roughly twice as high as that in cells undergoing slow exponential growth. The data indicate that the stationary-phase nucleoid is permeable to RNAP and suggest that it is permeable to ribosomal subunits. There appears to be no need to postulate migration of actively transcribed genes to the nucleoid periphery. IMPORTANCE Bacteria in nature usually lack sufficient nutrients to enable growth and replication. Such starved bacteria adapt into a quiescent state known as the stationary phase. The chromosomal DNA is protected against oxidative damage, and ribosomes are stored in a dimeric structure impervious to digestion. Stationary-phase bacteria can recover and grow quickly when better nutrient conditions arise. The biochemistry of stationary-phase E. coli is reasonably well understood. Here, we present results from a study of the biophysical state of starved E. coli. Superresolution fluorescence microscopy enables high-resolution location and tracking of a DNA locus and of single copies of RNA polymerase (the transcription machine) and ribosomes (the translation machine) in intact E. coli cells maintained in stationary phase. Evidently, the chromosomal DNA remains sufficiently permeable to enable transcription and translation to occur. This description contrasts with the usual picture of a rigid stationary-phase cytoplasm with highly condensed DNA.

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