Use of a Coulter Counter to Detect Discrete Changes in Cell Numbers and Volume During Growth of <i>Escherichia coli</i>

Smither, R.

doi:10.1111/j.1365-2672.1975.tb00557.x

Cited by 17 publications

(6 citation statements)

References 16 publications

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“…In the LC-MS/MS assay, each sample had 2 × 10 9 cells using 1 μm 3 as the cellular volume of E. coli . 55 , 82 The cellular concentration was calculated on the basis of the calculation in a previous study from Cai et al 55 Thus, the total volume of E. coli 2 × 10 9 cells is 2 μL [(2 × 10 9 ) × 1 μm 3 = 2 × 10 9 μm 3 = 2 μL (1 mL = 1 × 10 12 μm 3 )]. Therefore, the cellular concentration was equal to the measured concentration using LC-MS/MS (in μM) multiplied by the extraction volume (150 μL) and divided by the total cellular volume per sample (2 μL).…”

Section: Methodsmentioning

confidence: 99%

Fluorescent Trimethoprim Conjugate Probes To Assess Drug Accumulation in Wild Type and Mutant Escherichia coli

et al. 2016

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Reduced susceptibility to antimicrobials in Gram-negative bacteria may result from multiple resistance mechanisms, including increased efflux pump activity or reduced porin protein expression. Up-regulation of the efflux pump system is closely associated with multidrug resistance (MDR). To help investigate the role of efflux pumps on compound accumulation, a fluorescence-based assay was developed using fluorescent derivatives of trimethoprim (TMP), a broad-spectrum synthetic antibiotic that inhibits an intracellular target, dihydrofolate reductase (DHFR). Novel fluorescent TMP probes inhibited eDHFR activity with comparable potency to TMP, but did not kill or inhibit growth of wild type Escherichia coli. However, bactericidal activity was observed against an efflux pump deficient E. coli mutant strain (ΔtolC). A simple and quick fluorescence assay was developed to measure cellular accumulation of the TMP probe using either fluorescence spectroscopy or flow cytometry, with validation by LC-MS/MS. This fluorescence assay may provide a simple method to assess efflux pump activity with standard laboratory equipment.

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Section: Methodsmentioning

confidence: 99%

Fluorescent Trimethoprim Conjugate Probes To Assess Drug Accumulation in Wild Type and Mutant Escherichia coli

et al. 2016

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“…Alternatively, commercially available Coulter Counters have been used to monitor growth of small bacterial cell populations (7,8). These studies were carried out in the 1970s, and the focus was to examine cell populations at lower concentrations, which are not detectable with turbidimetry or nephelometry measurements.…”

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confidence: 99%

Mass and Density Measurements of Live and Dead Gram-Negative and Gram-Positive Bacterial Populations

Lewis

Craig

Senecal

2014

Appl Environ Microbiol

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Monitoring cell growth and measuring physical features of food-borne pathogenic bacteria are important for better understanding the conditions under which these organisms survive and proliferate. To address this challenge, buoyant masses of live and dead Escherichia coli O157:H7 and Listeria innocua were measured using Archimedes, a commercially available suspended microchannel resonator (SMR). Cell growth was monitored with Archimedes by observing increased cell concentration and buoyant mass values of live growing bacteria. These growth data were compared to optical density measurements obtained with a Bioscreen system. We observed buoyant mass measurements with Archimedes at cell concentrations between 10 5 and 10 8 cells/ ml, while growth was not observed with optical density measurements until the concentration was 10 7 cells/ml. Buoyant mass measurements of live and dead cells with and without exposure to hydrogen peroxide stress were also compared; live cells generally had a larger buoyant mass than dead cells. Additionally, buoyant mass measurements were used to determine cell density and total mass for both live and dead cells. Dead E. coli cells were found to have a larger density and smaller total mass than live E. coli cells. In contrast, density was the same for both live and dead L. innocua cells, while the total mass was greater for live than for dead cells. These results contribute to the ongoing challenge to further develop existing technologies used to observe cell populations at low concentrations and to measure unique physical features of cells that may be useful for developing future diagnostics.

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“…The Coulter counter measures the variations of impedance due to the transit of particles through a small hole in a membrane separating two electrolyte solutions. This has been successfully used to measure low bacterial concentrations 9,10 and growth rates of small populations in low glucose concentration. 11 The flow cytometer measures the light scattered by individual cells flowing through a capillary: it is suitable for counting microbes and can be extended to the study of phenotypic traits using fluorescent markers.…”

Section: A Sample and Count Methodsmentioning

confidence: 99%

Monitoring microbial population dynamics at low densities

Julou¹,

Desprat

Bensimon

et al. 2012

Review of Scientific Instruments

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We propose a new and simple method for the measurement of microbial concentrations in highly diluted cultures. This method is based on an analysis of the intensity fluctuations of light scattered by microbial cells under laser illumination. Two possible measurement strategies are identified and compared using simulations and measurements of the concentration of gold nanoparticles. Based on this comparison, we show that the concentration of Escherichia coli and Saccharomyces cerevisiae cultures can be easily measured in situ across a concentration range that spans five orders of magnitude. The lowest measurable concentration is three orders of magnitude (1000×) smaller than in current optical density measurements. We show further that this method can also be used to measure the concentration of fluorescent microbial cells. In practice, this new method is well suited to monitor the dynamics of population growth at early colonization of a liquid culture medium. The dynamic data thus obtained are particularly relevant for microbial ecology studies.

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Use of a Coulter Counter to Detect Discrete Changes in Cell Numbers and Volume During Growth of Escherichia coli

Cited by 17 publications

References 16 publications

Fluorescent Trimethoprim Conjugate Probes To Assess Drug Accumulation in Wild Type and Mutant Escherichia coli

Fluorescent Trimethoprim Conjugate Probes To Assess Drug Accumulation in Wild Type and Mutant Escherichia coli

Mass and Density Measurements of Live and Dead Gram-Negative and Gram-Positive Bacterial Populations

Monitoring microbial population dynamics at low densities

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