scholarly journals Environmental conditions define the energetics of bacterial dormancy and its antibiotic susceptibility

2020 ◽  
Author(s):  
L Mancini ◽  
T Pilizota
Keyword(s):  
Drug Susceptibility ◽  
Cell Physiology ◽  
Environmental Cues ◽  
Bacterial Cells ◽  
Infection Site ◽  
Persister Cells ◽  
Energy Profiles ◽  
Dormant Cells ◽  
Clinical Interest ◽  
High Concentrations

ABSTRACTBacterial cells that halt growth but maintain viability and the capacity to regrow are termed dormant and have been shown to transiently tolerate high concentrations of antimicrobials. Dormancy has been seen in both tolerant and persister cells and is therefore of substantial clinical interest, as both can lead to infection recalcitrance and facilitate the development of antibiotic resistance. In this work, we look at dormancies induced by environmental cues that target different aspects of cell physiology by measuring the energy profiles they elicit in single dormant cells. Our simultaneous measurements of ATP concentration, proton motive force (PMF) and cytoplasmic pH reveal that dormant cells can exist in various energy states, offering a solution to the apparent mutual incompatibility of previous experimental results. We then test whether the energetic makeup is associated with survival to antibiotics of different classes. We find that for certain drugs growth arrest remains the dominant mechanism enabling survival, while for others, like ciprofloxacin, the most energetic cells remain almost untouched by the drug. Our results support a novel relationship between environment and drug susceptibility of dormant cells and suggest that knowledge of the conditions present at the infection site is necessary to design appropriate treatments.

scholarly journals Persister cells mediate tolerance to metal oxyanions in Escherichia coli

Microbiology ◽  
2005 ◽  
Vol 151 (10) ◽  
pp. 3181-3195 ◽  
Author(s):  
Joe J. Harrison ◽  
Howard Ceri ◽  
Nicole J. Roper ◽  
Erin A. Badry ◽  
Kimberley M. Sproule ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Viable Cell ◽  
Small Population ◽  
Water Soluble ◽  
Bacterial Cells ◽  
Persister Cells ◽  
Term Survival ◽  
E Coli ◽  
Cell Counts ◽  
High Concentrations

Bacterial cultures produce subpopulations of cells termed ‘persisters’, reputedly known for high tolerance to killing by antibiotics. Ecologically, antibiotics produced by competing microflora are only one potential stress encountered by bacteria. Another pressure in the environment is toxic metals that are distributed ubiquitously by human pollution, volcanic activity and the weathering of minerals. This study evaluated the time- and concentration-dependent killing of Escherichia coli planktonic and biofilm cultures by the water-soluble metal(loid) oxyanions chromate (), arsenate (), arsenite (), selenite (), tellurate () and tellurite (). Correlative to previous reports in the literature, control antibiotic assays indicated that a small proportion of E. coli biofilm populations remained recalcitrant to killing by antibiotics (even with 24 h exposure). In contrast, metal oxyanions presented a slow, bactericidal action that eradicated biofilms. When exposed for 2 h, biofilms were up to 310 times more tolerant to killing by metal oxyanions than corresponding planktonic cultures. However, by 24 h, planktonic cells and biofilms were eradicated at approximately the same concentration in all instances. Coloured complexes of metals and chelators could not be generated in biofilms exposed to or , suggesting that the extracellular polymeric matrix of E. coli may have a low binding affinity for metal oxyanions. Viable cell counts at 2 and 24 h exposure revealed that, at high concentrations, all of the metal oxyanions had killed 99 % (or a greater proportion) of the bacterial cells in biofilm populations. It is suggested here that the short-term survival of <1 % of the bacterial population corresponds well with the hypothesis that a small population of persister cells may be responsible for the time-dependent tolerance of E. coli biofilms to high concentrations of metal oxyanions.

scholarly journals Persister Cells Resuscitate via Ribosome Modification by 23S rRNA Pseudouridine Synthase RluD

2019 ◽  
Author(s):  
Sooyeon Song ◽  
Thomas K. Wood
Keyword(s):  
Escherichia Coli ◽  
Small Rna ◽  
23S Rrna ◽  
Bacterial Cells ◽  
Persister Cells ◽  
E Coli ◽  
Pseudouridine Synthase ◽  
Dormant Cells ◽  
Wide Range ◽  
Persister Cell

ABSTRACTUpon a wide range of stress conditions (e.g., nutrient, antibiotic, oxidative), a subpopulation of bacterial cells known as persisters survive by halting metabolism. These cells resuscitate rapidly to reconstitute infections once the stress is removed and nutrients are provided. However, how these dormant cells resuscitate is not understood well but involves reactivating ribosomes. By screening 10,000 compounds directly for stimulating Escherichia coli persister cell resuscitation, we identified that 2-{[2-(4-bromophenyl)-2-oxoethyl]thio}-3-ethyl-5,6,7,8-tetrahydro[1]benzothieno[2,3-d]pyrimidin-4(3H)-one (BPOET) stimulates resuscitation. Critically, by screening 4,267 E. coli proteins, we determined that BPOET activates hibernating ribosomes via 23S rRNA pseudouridine synthase RluD, which increases ribosome activity. Corroborating the increased waking with RluD, production of RluD increased the number of active ribosomes in persister cells. Also, inactivating the small RNA RybB which represses rluD led to faster persister resuscitation. Hence, persister cells resuscitate via activation of RluD.

scholarly journals On the Effects of Doping on the Catalytic Performance of (La,Sr)CoO3. A DFT Study of CO Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 312 ◽  
Author(s):  
Antonella Glisenti ◽  
Andrea Vittadini
Keyword(s):  
Catalytic Activity ◽  
Co Oxidation ◽  
Density Functional Calculations ◽  
Density Functional ◽  
Formation Energy ◽  
Oxygen Vacancies ◽  
Catalytic Performance ◽  
Energy Profiles ◽  
High Concentrations ◽  
3D Impurities

The effects of modifying the composition of LaCoO3 on the catalytic activity are predicted by density functional calculations. Partially replacing La by Sr ions has benefical effects, causing a lowering of the formation energy of O vacancies. In contrast to that, doping at the Co site is less effective, as only 3d impurities heavier than Co are able to stabilize vacancies at high concentrations. The comparison of the energy profiles for CO oxidation of undoped and of Ni-, Cu-m and Zn-doped (La,Sr)CoO3(100) surface shows that Cu is most effective. However, the effects are less spectacular than in the SrTiO3 case, due to the different energetics for the formation of oxygen vacancies in the two hosts.

scholarly journals Effect of Pseudomonas moorei KB4 Cells’ Immobilisation on Their Degradation Potential and Tolerance towards Paracetamol

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 820
Author(s):  
Robert Surma ◽  
Danuta Wojcieszyńska ◽  
Jagna Karcz ◽  
Urszula Guzik
Keyword(s):  
Protective Effect ◽  
Kinetic Parameters ◽  
Toxicity Assessment ◽  
Bacterial Cells ◽  
Low Concentrations ◽  
Toxicity Analysis ◽  
Immobilised Cells ◽  
Degradation Activity ◽  
High Concentrations ◽  
The Hill

Pseudomonas moorei KB4 is capable of degrading paracetamol, but high concentrations of this drug may cause an accumulation of toxic metabolites. It is known that immobilisation can have a protective effect on bacterial cells; therefore, the toxicity and degradation rate of paracetamol by the immobilised strain KB4 were assessed. Strain KB4 was immobilised on a plant sponge. A toxicity assessment was performed by measuring the concentration of ATP using the colony-forming unit (CFU) method. The kinetic parameters of paracetamol degradation were estimated using the Hill equation. Toxicity analysis showed a protective effect of the carrier at low concentrations of paracetamol. Moreover, a pronounced phenomenon of hormesis was observed in the immobilised systems. The obtained kinetic parameters and the course of the kinetic curves clearly indicate a decrease in the degradation activity of cells after their immobilisation. There was a delay in degradation in the systems with free cells without glucose and immobilised cells with glucose. However, it was demonstrated that the immobilised systems can degrade at least ten succeeding cycles of 20 mg/L paracetamol degradation. The obtained results indicate that the immobilised strain may become a useful tool in the process of paracetamol degradation.

scholarly journals The Real-Time-Based Assessment of the Microbial Killing by the Antimicrobial Compounds of Neutrophils

2011 ◽  
Vol 11 ◽  
pp. 2382-2390 ◽  
Author(s):  
J. T. Atosuo ◽  
E.-M. Lilius
Keyword(s):  
Real Time ◽  
Antimicrobial Agents ◽  
Hypochlorous Acid ◽  
Bacterial Cells ◽  
Photorhabdus Luminescens ◽  
Bacterial Luciferase ◽  
E Coli ◽  
High Concentrations ◽  
Time Basis ◽  
K 12

A recombinantEscherichia coliK-12 strain, transformed with a modified bacterial luciferase gene (luxABCDE) fromPhotorhabdus luminescens, was constructed in order to monitor the activity of various antimicrobial agents on a real-time basis. ThisE. coli-lux emitted, without any addition of substrate, constitutive bioluminescence (BL), which correlated to the number of viable bacterial cells. The decrease in BL signal correlated to the number of killed bacterial cells. Antimicrobial activity of hydrogen peroxide (H2O2) and myeloperoxidase (MPO) was assessed. In high concentrations, H2O2alone had a bacteriocidic function and MPO enhanced this killing by forming hypochlorous acid (HOCl). Taurine, the known HOCl scavenger, blocked the killing by MPO. WhenE. coli-lux was incubated with neutrophils, similar killing kinetics was recorded as in H2O2/MPO experiments. The opsonization of bacteria enhanced the killing, and the maximum rate of the MPO release from lysosomes coincided with the onset of the killing.

Anaerobic Treatment of Industrial Wastewater Containing Organic Solvents

1994 ◽  
Vol 29 (9) ◽  
pp. 321-329 ◽  
Author(s):  
Evangelos Terzis
Keyword(s):  
Anaerobic Digestion ◽  
Organic Solvents ◽  
Industrial Effluent ◽  
Maximum Growth ◽  
Anaerobic Treatment ◽  
Maximum Growth Rate ◽  
Bacterial Cells ◽  
Precise Control ◽  
Water Charges ◽  
High Concentrations

Industrial water usage results in large volumes of liquid wastes rich in organic pollutants. Waste waters from certain industrial chemical operations (e.g. organic synthesis, perfume industry) will sometimes contain organic solvents at relatively high concentrations. The presence of organic solvents is undesirable in the sewerage system and so must be removed from the industrial effluent. Anaerobic treatment of many of these organic solvents is possible, in which the organic material is converted ~90% to volatile substances -carbon dioxide and methane gas- and ~10% to new bacterial cells (solids). Industry will be using less water in the future. Increased water charges will lead to more precise control and integrated processes will reduce wastage. The smaller volumes of more concentrated waste will be ideal for anaerobic digestion. In order to evaluate the optimum conditions for the anaerobic digestion of propan-2-ol (iso-propanol) the kinetic parameters of the Monod rate model, namely, maximum growth rate (µm), yield (Y), half velocity constant (Ks) and endogenous decay coefficient (Kd), were determined at the temperature range 25°-40°C, inclusively. The regulatory role of molecular hydrogen was investigated and discussed, and also its possible use as a monitor feature in the anaerobic digestion.

scholarly journals Mode of Action of the Antimicrobial Peptide Aureocin A53 from Staphylococcus aureus

2002 ◽  
Vol 68 (11) ◽  
pp. 5274-5280 ◽  
Author(s):  
Daili Jacqueline Aguilar Netz ◽  
Maria do Carmo de Freire Bastos ◽  
Hans-Georg Sahl
Keyword(s):  
Mode Of Action ◽  
Neutral Lipids ◽  
Membrane Damage ◽  
Model Membranes ◽  
Bacterial Cells ◽  
Gram Staining ◽  
Rapid Release ◽  
High Concentrations ◽  
Staphylococcus Simulans ◽  
Tryptophan Emission

ABSTRACT We investigated the mode of action of aureocin A53 on living bacterial cells and model membranes. Aureocin A53 acted bactericidally against Staphylococcus simulans 22, with >90% of the cells killed within a few minutes. Cell death was followed by lysis, as indicated by a clearing of the cell suspension and Gram staining. Aureocin A53 rapidly dissipated the membrane potential and simultaneously stopped biosynthesis of DNA, polysaccharides, and protein. Aureocin A53 induced a rapid release of preaccumulated glutamate and Rb+. Experiments on model membranes demonstrated that aureocin A53 provoked significant leakage of carboxyfluorescein (CF) exclusively from acidic liposomes but only at relatively high concentrations (0.5 to 8 mol%). Thus, the bactericidal activity of aureocin A53 derives from membrane permeation via generalized membrane destruction rather than by formation of discrete pores within membranes. Tryptophan emission fluorescence spectroscopy demonstrated interaction of aureocin A53 with both acidic and neutral membranes, as indicated by similar blue shifts. Since there was no significant aureocin A53-induced CF leakage from neutral liposomes, its appears that the peptide does interact with neutral lipids without provoking membrane damage.

scholarly journals Dosing Regimen Matters: the Importance of Early Intervention and Rapid Attainment of the Pharmacokinetic/Pharmacodynamic Target

2012 ◽  
Vol 56 (6) ◽  
pp. 2795-2805 ◽  
Author(s):  
Marilyn N. Martinez ◽  
Mark G. Papich ◽  
George L. Drusano
Keyword(s):  
Steady State ◽  
Resistant Bacteria ◽  
Infection Site ◽  
Dosing Regimen ◽  
Persister Cells ◽  
Published Evidence ◽  
Drug Concentrations ◽  
Selection Window ◽  
Microbial Strains ◽  
Systemic Drug

ABSTRACTTo date, the majority of pharmacokinetic/pharmacodynamic (PK/PD) discussions have focused on PK/PD relationships evaluated at steady-state drug concentrations. However, a concern with reliance upon steady-state drug concentrations is that it ignores events occurring while the pathogen is exposed to intermittent suboptimal systemic drug concentrations prior to the attainment of a steady state. Suboptimal (inadequate) exposure can produce amplification of resistant bacteria. This minireview provides an overview of published evidence supporting the positions that, in most situations, it is the exposure achieved during the first dose that is relevant for determining the therapeutic outcome of an infection, therapeutic intervention should be initiated as soon as possible to minimize the size of the bacterial burden at the infection site, and the duration of drug administration should be kept as brief as clinically appropriate to reduce the risk of selecting for resistant (or phenotypically nonresponsive) microbial strains. To support these recommendations, we briefly discuss data on inoculum effects, persister cells, and the concept of time within some defined mutation selection window.

Attachment of Salmonella to mammalian cells in vitro

1983 ◽  
Vol 29 (12) ◽  
pp. 1731-1735 ◽  
Author(s):  
Clifford S. Mintz ◽  
Dean O. Cliver ◽  
R. H. Deibel
Keyword(s):  
Cell Lines ◽  
Mammalian Cells ◽  
Culture Cell ◽  
Intestinal Cell ◽  
Tissue Culture Cell ◽  
Bacterial Cells ◽  
Intestinal Cell Line ◽  
Hela Cell Lines ◽  
High Concentrations

The attachment of Salmonella typhimurium strain PHL67342 to several mammalian tissue culture cell lines was investigated. Strain PHL67342 failed to attach in significant numbers to the Buffalo green monkey (BGM), swine testicular (ST), and HeLa cell lines. Significant attachment was observed with the Henle intestinal cell line. Log-phase cells of strain PHL67342 attached in greatest numbers to the Henle cells after 45 min of incubation at 37 °C. Attachment to the Henle cells was not affected by D-mannose or D-galactose, but was markedly inhibited by high concentrations of alpha-methyl-D-mannoside. Also, Salmonella lipopolysaccharide had no effect on the attachment of strain PHL67342 to the Henle cells. Fimbriae were not detected on the bacterial cells used in the adherence experiments. These results suggest that some bacterial factor(s) other than fimbriae and lipopolysaccharide mediate the attachment of strain PHL67342 to the Henle cells.

scholarly journals Antibiotic in myrrh from Commiphora molmol preferentially kills nongrowing bacteria

2020 ◽  
pp. FSO458
Author(s):  
Mrinal K Bhattacharjee ◽  
Tahrir Alenezi
Keyword(s):  
Growth Inhibition ◽  
Soft Agar ◽  
Bacterial Cells ◽  
Persister Cells ◽  
Resistance Development ◽  
Development Method ◽  
Continue Growth

Aim: To demonstrate that myrrh oil preferentially kills nongrowing bacteria and causes no resistance development. Method: Growth inhibition was determined on regular plates or plates without nutrients, which were later overlaid with soft agar containing nutrients to continue growth. Killing experiments were done in broth and in buffer without nutrients. Results: Bacterial cells were inhibited preferentially in the absence of nutrients or when growth was halted by a bacteriostatic antibiotic. After five passages in myrrh oil, surviving colonies showed no resistance to the antibiotic. Conclusion: Myrrh oil has the potential to be a commercially viable antibiotic that kills persister cells and causes no resistance development. This is a rare example of an antibiotic that can preferentially kill nongrowing bacteria.

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