scholarly journals Actively growing cells are the predominant persisters in exponential phase of Escherichia coli

2021 ◽  
Author(s):  
Miki Umetani ◽  
Miho Fujisawa ◽  
Reiko Okura ◽  
Takashi Nozoe ◽  
Shoichi Suenaga ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Drug Exposure ◽  
Culture Media ◽  
Morphological Changes ◽  
Lethal Dose ◽  
Exponential Phase ◽  
Cell Lineages ◽  
Dormant Cells ◽  
Persistent Cell

Bacterial persistence is a phenomenon in which a small fraction of isogenic bacterial cells survives a lethal dose of antibiotics. It is generally assumed that persistence is caused by growth-arrested dormant cells generated prior to drug exposure. However, evidence from direct observation is scarce due to extremely low frequencies of persisters, and is limited to high persistence mutants or to conditions that significantly increase persister frequencies. Here, utilizing a microfluidic device with a membrane-covered microchamber array, we visualize the responses of more than 106 individual cells of wildtype Escherichia coli to lethal doses of antibiotics, sampling cells from different growth phases and culture media. We show that preexisting dormant persisters constitute only minor fractions of persistent cell lineages in populations sampled from exponential phase, and that most persistent cell lineages grew actively before drug exposure. Actively growing persisters exhibit radical morphological changes in response to drug exposure, including L-form-like morphologies or filamentation depending on antibiotic type, and restore their rod-like shape after drug removal. Incubating cells under stationary phase conditions increases both the frequency and the probability of survival of dormant cells. While dormant cells in late stationary phase express a general stress response regulator, RpoS, at high levels, persistent cell lineages tended to show low to moderate RpoS expression among the dormant cells. These results demonstrate that heterogeneous survival pathways may coexist within bacterial populations to achieve persistence and that persistence does not necessarily require dormant cells.

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.

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.

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.

Morphological changes during the growth cycle of axenic and monoxenic Tetrahymena pyriformis

1976 ◽  
Vol 54 (11) ◽  
pp. 2011-2018 ◽  
Author(s):  
William D. Taylor ◽  
Michael A. Gates ◽  
Jacques Berger
Keyword(s):  
Culture Media ◽  
Morphological Changes ◽  
Food Limitation ◽  
Food Resource ◽  
Tetrahymena Pyriformis ◽  
Growth Cycle ◽  
Exponential Phase ◽  
Type Ii ◽  
Axenic Medium ◽  
Morphological Differences

Morphometric data were collected from Tetrahymena pyriformis (WH-14, syngen I, mating type II) grown in two different media, one axenic and one monoxenic (with Serratia marcescens), at various times during the growth cycle. Stationary phase cells differed morphometrically from exponential phase cells in different ways in the two media. It is proposed that, in the monoxenic medium, division stopped because the food resource was depleted, while in the axenic medium division was blocked before food limitation occurred.Cells in the two culture media showed consistent morphological differences during exponential phase, the axenic cells being larger (length and width), but having smaller (in length) mouths. Significant differences between cells in replicate experiments were frequently observed.

Augmentation of Killing of Escherichia coli O157 by Combinations of Lactate, Ethanol, and Low-pH Conditions

1999 ◽  
Vol 65 (3) ◽  
pp. 1308-1311 ◽  
Author(s):  
Sarah L. Jordan ◽  
Jayne Glover ◽  
Laura Malcolm ◽  
Fiona M. Thomson-Carter ◽  
Ian R. Booth ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Acid Tolerance ◽  
Low Ph ◽  
Exponential Phase ◽  
Escherichia Coli O157 ◽  
Cytoplasmic Ph ◽  
Ph Homeostasis ◽  
Acid Tolerant ◽  
Ph Conditions

ABSTRACT The acid tolerance of Escherichia coli O157:H7 strains can be overcome by addition of lactate, ethanol, or a combination of the two agents. Killing can be increased by as much as 4 log units in the first 5 min of incubation at pH 3 even for the most acid-tolerant isolates. Exponential-phase, habituated, and stationary-phase cells are all sensitive to incubation with lactate and ethanol. Killing correlates with disruption of the capacity for pH homeostasis. Habituated and stationary-phase cells can partially offset the effects of the lowering of cytoplasmic pH.

scholarly journals Role and Regulation of σs in General Resistance Conferred by Low-Shear Simulated Microgravity in Escherichia coli

2004 ◽  
Vol 186 (24) ◽  
pp. 8207-8212 ◽  
Author(s):  
S. V. Lynch ◽  
E. L. Brodie ◽  
A. Matin
Keyword(s):  
Escherichia Coli ◽  
Stationary Phase ◽  
Simulated Microgravity ◽  
Exponential Phase ◽  
Translational Efficiency ◽  
Potential Threat ◽  
Regulatory Processes ◽  
Human Immune Response ◽  
Life On Earth ◽  
Low Shear

ABSTRACT Life on Earth evolved in the presence of gravity, and thus it is of interest from the perspective of space exploration to determine if diminished gravity affects biological processes. Cultivation of Escherichia coli under low-shear simulated microgravity (SMG) conditions resulted in enhanced stress resistance in both exponential- and stationary-phase cells, making the latter superresistant. Given that microgravity of space and SMG also compromise human immune response, this phenomenon constitutes a potential threat to astronauts. As low-shear environments are encountered by pathogens on Earth as well, SMG-conferred resistance is also relevant to controlling infectious disease on this planet. The SMG effect resembles the general stress response on Earth, which makes bacteria resistant to multiple stresses; this response is σs dependent, irrespective of the growth phase. However, SMG-induced increased resistance was dependent on σs only in stationary phase, being independent of this sigma factor in exponential phase. σs concentration was some 30% lower in exponential-phase SMG cells than in normal gravity cells but was twofold higher in stationary-phase SMG cells. While SMG affected σs synthesis at all levels of control, the main reasons for the differential effect of this gravity condition on σs levels were that it rendered the sigma protein less stable in exponential phase and increased rpoS mRNA translational efficiency. Since σs regulatory processes are influenced by mRNA and protein-folding patterns, the data suggest that SMG may affect these configurations.

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.

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 Effects of Temperature, Growth Media, and Photoperiod on Growth and Toxin Production of Azadinium spinosum

Marine Drugs ◽  
2019 ◽  
Vol 17 (9) ◽  
pp. 489 ◽  
Author(s):  
Jane Kilcoyne ◽  
Amy McCoy ◽  
Stephen Burrell ◽  
Bernd Krock ◽  
Urban Tillmann
Keyword(s):  
Stationary Phase ◽  
Water Samples ◽  
Culture Media ◽  
Toxin Production ◽  
Exponential Phase ◽  
Growth Media ◽  
Temperature Growth ◽  
Effects Of Temperature ◽  
Cell Densities

Azaspiracids (AZAs) are microalgal toxins that can accumulate in shellfish and lead to human intoxications. To facilitate their study and subsequent biomonitoring, purification from microalgae rather than shellfish is preferable; however, challenges remain with respect to maximizing toxin yields. The impacts of temperature, growth media, and photoperiod on cell densities and toxin production in Azadinium spinosum were investigated. Final cell densities were similar at 10 and 18 °C, while toxin cell quotas were higher (~3.5-fold) at 10 °C. A comparison of culture media showed higher cell densities and AZA cell quotas (2.5–5-fold) in f10k compared to f/2 and L1 media. Photoperiod also showed differences, with lower cell densities in the 8:16 L:D treatment, while toxin cell quotas were similar for 12:12 and 8:16 L:D treatments but slightly lower for the 16:8 L:D treatment. AZA1, -2 and -33 were detected during the exponential phase, while some known and new AZAs were only detected once the stationary phase was reached. These compounds were additionally detected in field water samples during an AZA event.

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