scholarly journals Variation of Physiochemical Properties and Cell Association Activity of Membrane Vesicles with Growth Phase in Pseudomonas aeruginosa

2010 ◽  
Vol 76 (11) ◽  
pp. 3732-3739 ◽  
Author(s):  
Yosuke Tashiro ◽  
Sosaku Ichikawa ◽  
Motoyuki Shimizu ◽  
Masanori Toyofuku ◽  
Naoki Takaya ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Stationary Phase ◽  
Stationary Phases ◽  
Membrane Vesicles ◽  
Exponential Phase ◽  
Phase Changes ◽  
Bacterial Cells ◽  
Physiochemical Properties ◽  
Cell Association ◽  
Phase Surface

ABSTRACT Pseudomonas aeruginosa and other Gram-negative bacteria release membrane vesicles (MVs) from their surfaces, and MVs have an ability to interact with bacterial cells. Although it has been known that many bacteria have mechanisms that control their phenotypes with the transition from exponential phase to stationary phase, changes of properties in released MVs have been poorly understood. Here, we demonstrate that MVs released by P. aeruginosa during the exponential and stationary phases possess different physiochemical properties. MVs purified from the stationary phase had higher buoyant densities than did those purified from the exponential phase. Surface charge, characterized by zeta potential, of MVs tended to be more negative as the growth shifted to the stationary phase, although the charges of PAO1 cells were not altered. Pseudomonas quinolone signal (PQS), one of the regulators related to MV production in P. aeruginosa, was lower in MVs purified from the exponential phase than in those from the stationary phase. MVs from the stationary phase more strongly associated with P. aeruginosa cells than did those from the exponential phase. Our findings suggest that properties of MVs are altered to readily interact with bacterial cells along with the growth transition in P. aeruginosa.

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.

Regulation of expression of the cyanide-insensitive terminal oxidase in Pseudomonas aeruginosa

Microbiology ◽  
2003 ◽  
Vol 149 (5) ◽  
pp. 1275-1284 ◽  
Author(s):  
Megan Cooper ◽  
Gholam Reza Tavankar ◽  
Huw D. Williams
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Stationary Phase ◽  
Culture Medium ◽  
Homoserine Lactone ◽  
Exponential Phase ◽  
Terminal Oxidase ◽  
Regulation Of Expression ◽  
Potent Inducer ◽  
Protein Levels ◽  
In The Wild

The regulation of the cyanide-insensitive oxidase (CIO) in Pseudomonas aeruginosa, a bacterium that can synthesize HCN, is reported. The expression of a cioA–lacZ transcriptional fusion, CioA protein levels and CIO activity were low in exponential phase but induced about fivefold upon entry into stationary phase. Varying the O2 transfer coefficient from 11·5 h−1 to 87·4 h−1 had no effect on CIO expression and no correlation was observed between CIO induction and the dissolved O2 levels in the growth medium. However, a mutant deleted for the O2-sensitive transcriptional regulator ANR derepressed CIO expression in an O2-sensitive manner, with the highest induction occurring under low-O2 conditions. Therefore, CIO expression can respond to a signal generated by low O2 levels, but this response is normally kept in check by ANR repression. ANR may play an important role in preventing overexpression of the CIO in relation to other terminal oxidases. A component present in spent culture medium was able to induce CIO expression. However, experiments with purified N-butanoyl-l-homoserine lactone or N-(3-oxododecanoyl)homoserine lactone ruled out a role for these quorum-sensing molecules in the control of CIO expression. Cyanide was a potent inducer of the CIO at physiologically relevant concentrations and experiments using spent culture medium from a ΔhcnB mutant, which is unable to synthesize cyanide, showed that cyanide was the inducing factor present in P. aeruginosa spent culture medium. However, the finding that in a ΔhcnB mutant cioA–lacZ expression was induced normally upon entry into stationary phase indicated that cyanide was not the endogenous inducer of the terminal oxidase. The authors suggest that the failure of O2 to have an effect on CIO expression in the wild-type can be explained either by the requirement for an additional, stationary-phase-specific inducing signal or by the loss of an exponential-phase-specific repressing signal.

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.

scholarly journals Deletion of the parA (soj) Homologue in Pseudomonas aeruginosa Causes ParB Instability and Affects Growth Rate, Chromosome Segregation, and Motility

2007 ◽  
Vol 189 (15) ◽  
pp. 5762-5772 ◽  
Author(s):  
Krzysztof Lasocki ◽  
Aneta A. Bartosik ◽  
Jolanta Mierzejewska ◽  
Christopher M. Thomas ◽  
Grazyna Jagura-Burdzy
Keyword(s):  
Amino Acids ◽  
Growth Rate ◽  
Pseudomonas Aeruginosa ◽  
Stationary Phase ◽  
Chromosome Segregation ◽  
Turnover Rate ◽  
Exponential Phase ◽  
Full Length ◽  
Cytosolic Protein

ABSTRACT The parA and parB genes of Pseudomonas aeruginosa are located approximately 8 kb anticlockwise from oriC. ParA is a cytosolic protein present at a level of around 600 molecules per cell in exponential phase, but the level drops about fivefold in stationary phase. Overproduction of full-length ParA or the N-terminal 85 amino acids severely inhibits growth of P. aeruginosa and P. putida. Both inactivation of parA and overexpression of parA in trans in P. aeruginosa also lead to accumulation of anucleate cells and changes in motility. Inactivation of parA also increases the turnover rate (degradation) of ParB. This may provide a mechanism for controlling the level of ParB in response to the growth rate and expression of the parAB operon.

Changes of trehalose content and expression of relative genes during the bioethanol fermentation bySaccharomyces cerevisiae

2016 ◽  
Vol 62 (10) ◽  
pp. 827-835 ◽  
Author(s):  
Chenfeng Yi ◽  
Fenglian Wang ◽  
Shijun Dong ◽  
Hao Li
Keyword(s):  
Phase Transition ◽  
Stationary Phase ◽  
Ethanol Tolerance ◽  
Stationary Phases ◽  
Exponential Phase ◽  
Yeast Cells ◽  
Ethanol Stress ◽  
Lag Phase ◽  
Significant Difference ◽  
Trehalose Content

Traditionally, trehalose is considered as a protectant to improve the ethanol tolerance of Saccharomyces cerevisiae. In this study, to clarify the changes and roles of trehalose during the bioethanol fermentation, trehalose content and expression of related genes at lag, exponential, and stationary phases (i.e., 2, 8, and 16 h of batch fermentation process) were determined. Although yeast cells at exponential and stationary phase had higher trehalose content than cells at lag phase (P < 0.01), there was no significant difference in trehalose content between exponential and stationary phases (P > 0.05). Moreover, expression of the trehalose degradation-related genes NTH1 and NTH2 decreased at exponential phase in comparison with that at lag phase; compared with cells at lag phase, cells at stationary phase had higher expression of TPS1, ATH1, NTH1, and NTH2 but lower expression of TPS2. During the lag–exponential phase transition, downregulation of NTH1 and NTH2 promoted accumulation of trehalose, and to some extent, trehalose might confer ethanol tolerance to S. cerevisiae before stationary phase. During the exponential–stationary phase transition, upregulation of TPS1 contributed to accumulation of trehalose, and Tps1 protein might be indispensable in yeast cells to withstand ethanol stress at the stationary phase. Moreover, trehalose would be degraded to supply carbon source at stationary phase.

scholarly journals Taxon- and Growth Phase-Specific Antioxidant Production by Chlorophyte, Bacillariophyte, and Haptophyte Strains Isolated From Tropical Waters

2020 ◽  
Vol 8 ◽  
Author(s):  
Norazira Abdu Rahman ◽  
Tomoyo Katayama ◽  
Mohd Effendy Abd Wahid ◽  
Nor Azman Kasan ◽  
Helena Khatoon ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Stationary Phase ◽  
Antioxidant Capacity ◽  
Growth Phase ◽  
Stationary Phases ◽  
Exponential Phase ◽  
Antioxidant Compounds ◽  
Antioxidant Compound ◽  
Scavenging Capacity ◽  
Β Carotene

Antioxidants found in microalgae play an essential role in both animals and humans, against various diseases and aging processes by protecting cells from oxidative damage. In this study, 26 indigenous tropical marine microalgae were screened. Out of the 26 screened strains, 10 were selected and were further investigated for their natural antioxidant compounds which include carotenoids, phenolics, and fatty acids collected in their exponential and stationary phases. The antioxidant capacity was also evaluated by a total of four assays, which include ABTS, DPPH, superoxide radical (O2•–) scavenging capacity, and nitric oxide (•NO–) scavenging capacity. This study revealed that the antioxidant capacity of the microalgae varied between divisions, strains, and growth phase and was also related to the content of antioxidant compounds present in the cells. Carotenoids and phenolics were found to be the major contributors to the antioxidant capacity, followed by polyunsaturated fatty acids linoleic acid (LA), eicosapentaenoic acid (EPA), arachidonic acid (ARA), and docosahexaenoic acid (DHA) compared to other fatty acids. The antioxidant capacity of the selected bacillariophytes and haptophytes was found to be positively correlated to phenolic (R2-value = 0.623, 0.714, and 0.786 with ABTS, DPPH, and •NO–) under exponential phase, and to carotenoid fucoxanthin and β-carotene (R2 value = 0.530, 0.581 with ABTS, and 0.710, 0.795 with O2•–) under stationary phase. Meanwhile, antioxidant capacity of chlorophyte strains was positively correlated with lutein, β-carotene and zeaxanthin under the exponential phase (R2 value = 0.615, 0.615, 0.507 with ABTS, and R2 value = 0.794, 0.659, and 0.509 with •NO–). In the stationary phase, chlorophyte strains were positively correlated with violaxanthin (0.755 with •NO–), neoxanthin (0.623 with DPPH, 0.610 with •NO–), and lutein (0.582 with •NO–). This study showed that antioxidant capacity and related antioxidant compound production of tropical microalgae strains are growth phase-dependent. The results can be used to improve the microalgal antioxidant compound production for application in pharmaceutical, nutraceutical, food, and feed industry.

scholarly journals Measuring and modeling energy and power consumption in living microbial cells with a synthetic ATP reporter

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Yijie Deng ◽  
Douglas Raymond Beahm ◽  
Steven Ionov ◽  
Rahul Sarpeshkar
Keyword(s):  
Power Consumption ◽  
Stationary Phases ◽  
Energy Levels ◽  
Circuit Model ◽  
Exponential Phase ◽  
Bacterial Cells ◽  
Growth Phases ◽  
E Coli ◽  
Living Organisms ◽  
In Cells

Abstract Background Adenosine triphosphate (ATP) is the main energy carrier in living organisms, critical for metabolism and essential physiological processes. In humans, abnormal regulation of energy levels (ATP concentration) and power consumption (ATP consumption flux) in cells is associated with numerous diseases from cancer, to viral infection and immune dysfunction, while in microbes it influences their responses to drugs and other stresses. The measurement and modeling of ATP dynamics in cells is therefore a critical component in understanding fundamental physiology and its role in pathology. Despite the importance of ATP, our current understanding of energy dynamics and homeostasis in living cells has been limited by the lack of easy-to-use ATP sensors and the lack of models that enable accurate estimates of energy and power consumption related to these ATP dynamics. Here we describe a dynamic model and an ATP reporter that tracks ATP in E. coli over different growth phases. Results The reporter is made by fusing an ATP-sensing rrnB P1 promoter with a fast-folding and fast-degrading GFP. Good correlations between reporter GFP and cellular ATP were obtained in E. coli growing in both minimal and rich media and in various strains. The ATP reporter can reliably monitor bacterial ATP dynamics in response to nutrient availability. Fitting the dynamics of experimental data corresponding to cell growth, glucose, acetate, dissolved oxygen, and ATP yielded a mathematical and circuit model. This model can accurately predict cellular energy and power consumption under various conditions. We found that cellular power consumption varies significantly from approximately 0.8 and 0.2 million ATP/s for a tested strain during lag and stationary phases to 6.4 million ATP/s during exponential phase, indicating ~ 8–30-fold changes of metabolic rates among different growth phases. Bacteria turn over their cellular ATP pool a few times per second during the exponential phase and slow this rate by ~ 2–5-fold in lag and stationary phases. Conclusion Our rrnB P1-GFP reporter and kinetic circuit model provide a fast and simple way to monitor and predict energy and power consumption dynamics in bacterial cells, which can impact fundamental scientific studies and applied medical treatments in the future.

scholarly journals Gene expression of Pseudomonas aeruginosa in a mucin-containing synthetic growth medium mimicking cystic fibrosis lung sputum

2010 ◽  
Vol 59 (9) ◽  
pp. 1089-1100 ◽  
Author(s):  
Carina Fung ◽  
Sharna Naughton ◽  
Lynne Turnbull ◽  
Pholawat Tingpej ◽  
Barbara Rose ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Stationary Phase ◽  
Luria Broth ◽  
Exponential Phase ◽  
Anaerobic Growth ◽  
Phase Growth ◽  
Early Exponential Phase

Pseudomonas aeruginosa airway infection is the leading cause of morbidity and mortality in cystic fibrosis (CF) patients. Various in vitro models have been developed to study P. aeruginosa pathobiology in the CF lung. In this study we produced a modified artificial-sputum medium (ASMDM) more closely resembling CF sputum than previous models, and extended previous work by using strain PAO1 arrays to examine the global transcription profiles of P. aeruginosa strain UCBPP-PA14 under early exponential-phase and stationary-phase growth. In early exponential phase, 38/39 nutrition-related genes were upregulated in line with data from previous in vitro models using UCBPP-PA14. Additionally, 23 type III secretion system (T3SS) genes, several anaerobic respiration genes and 24 quorum-sensing (QS)-related genes were upregulated in ASMDM, suggesting enhanced virulence factor expression and priming for anaerobic growth and biofilm formation. Under stationary phase growth in ASMDM, macroscopic clumps resembling microcolonies were evident in UCBPP-PA14 and CF strains, and over 40 potentially important genes were differentially expressed relative to stationary-phase growth in Luria broth. Most notably, QS-related and T3SS genes were downregulated in ASMDM, and iron-acquisition and assimilatory nitrate reductase genes were upregulated, simulating the iron-depleted, microaerophilic/anaerobic environment of CF sputum. ASMDM thus appears to be highly suitable for gene expression studies of P. aeruginosa in CF.

scholarly journals Influence of Temperature and Growth Phase on Expression of a 104-Kilodalton Listeria Adhesion Protein inListeria monocytogenes

1999 ◽  
Vol 65 (6) ◽  
pp. 2765-2769 ◽  
Author(s):  
Nivia I. Santiago ◽  
Allan Zipf ◽  
Arun K. Bhunia
Keyword(s):  
Monoclonal Antibody ◽  
Stationary Phase ◽  
Stationary Phases ◽  
Surface Protein ◽  
Exponential Phase ◽  
Growth Phases ◽  
Adhesion Protein ◽  
Enhanced Expression ◽  
Temperature And Growth ◽  
Human Enterocyte

ABSTRACT Interaction of Listeria monocytogenes with mammalian intestinal cells is believed to be an important first step inListeria pathogenesis. Transposon (Tn916) mutagenesis provided strong evidence that a 104-kDa surface protein, designated the Listeria adhesion protein (LAP), was involved in adherence of L. monocytogenes to a human enterocyte-like Caco-2 cell line (V. Pandiripally, D. Westbrook, G. Sunki, and A. Bhunia, J. Med. Microbiol. 48:117–124, 1999). In this study, expression of LAP in L. monocytogenes at various growth temperatures (25, 37, and 42°C) and in various growth phases was determined by performing an enzyme-linked immunoassay (ELISA) and Western blotting with a specific monoclonal antibody (monoclonal antibody H7). The ELISA and Western blot results indicated that there was a significant increase in LAP expression over time only at 37 and 42°C and that the level of LAP expression was low during the exponential phase and high during the stationary phase. In contrast, there were not significant differences in LAP expression between the exponential and stationary phases at 25°C. Examination of the adhesion of L. monocytogenes cells from exponential-phase (12-h) or stationary-phase (24-h) cultures grown at 37°C to Caco-2 cells revealed that there were not significant differences in adhesion. Although expression of L. monocytogenes LAP was different at different growth temperatures and in different growth phases, enhanced expression did not result in increased adhesion, possibly because only a few LAP molecules were sufficient to initiate binding to Caco-2 cells.

scholarly journals Influence of Infected Cell Growth State on Bacteriophage Reactivation Levels

2000 ◽  
Vol 66 (12) ◽  
pp. 5206-5212 ◽  
Author(s):  
Dana R. Kadavy ◽  
Julie J. Shaffer ◽  
Susan E. Lott ◽  
Thomas A. Wolf ◽  
Cathy E. Bolton ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Cell Growth ◽  
Stationary Phase ◽  
Exponential Phase ◽  
Host Cells ◽  
Dark Repair ◽  
Repair Capacity ◽  
Growth State ◽  
Uv C ◽  
Starvation Conditions

ABSTRACT Reactivation of UV-C-inactivated Pseudomonas aeruginosabacteriophages D3C3, F116, G101, and UNL-1 was quantified in host cells infected during the exponential phase, during the stationary phase, and after starvation (1 day, 1 and 5 weeks) under conditions designed to detect dark repair and photoreactivation. Our experiments revealed that while the photoreactivation capacity of stationary-phase or starved cells remained about the same as that of exponential-phase cells, in some cases their capacity to support dark repair of UV-inactivated bacteriophages increased over 10-fold. This enhanced reactivation capacity was correlated with the ca. 30-fold-greater UV-C resistance ofP. aeruginosa host cells that were in the stationary phase or exposed to starvation conditions prior to irradiation. The dark repair capacity of P. aeruginosa cells that were infected while they were starved for prolonged periods depended on the bacteriophage examined. For bacteriophage D3C3 this dark repair capacity declined with prolonged starvation, while for bacteriophage G101 the dark repair capacity continued to increase when cells were starved for 24 h or 1 week prior to infection. For G101, the reactivation potentials were 16-, 18-, 10-, and 3-fold at starvation intervals of 1 day, 1 week, 5 weeks, and 1.5 years, respectively. Exclusive use of exponential-phase cells to quantify bacteriophage reactivation should detect only a fraction of the true phage reactivation potential.

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