Buoyant density of Escherichia coli is determined solely by the osmolarity of the culture medium

Baldwin, W W; Myer, Richard; Powell, Nicole D.; Anderson, Erika; Koch, Arthur L.

doi:10.1007/s002030050248

Cited by 28 publications

(19 citation statements)

References 8 publications

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“…To modify the density of YEPD (yeast extract/peptone supplemented with 2% glucose) we selected Percoll (Sigma-Aldrich), a colloidal silica suspension, for its low osmolality, low viscosity, and general impermeability of biological membranes (17). Experiments with Histodenz (Sigma-Aldrich) showed density changes for arrested yeast, likely through an osmotic response, such as is observed in bacteria (18). The resolution of the 8-μm-tall SMR used for these experiments is ∼3 fg (1-Hz bandwidth).…”

Section: Resultsmentioning

confidence: 96%

Measurement of mass, density, and volume during the cell cycle of yeast

Bryan

Goranov²,

Amon³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

254

192

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Cell growth comprises changes in both mass and volume-two processes that are distinct, yet coordinated through the cell cycle. Understanding this relationship requires a means for measuring each of the cell's three basic physical parameters: mass, volume, and the ratio of the two, density. The suspended microchannel resonator weighs single cells with a precision in mass of 0.1% for yeast. Here we use the suspended microchannel resonator with a Coulter counter to measure the mass, volume, and density of budding yeast cells through the cell cycle. We observe that cell density increases prior to bud formation at the G1/S transition, which is consistent with previous measurements using density gradient centrifugation. To investigate the origin of this density increase, we monitor relative density changes of growing yeast cells. We find that the density increase requires energy, function of the protein synthesis regulator target of rapamycin, passage through START (commitment to cell division), and an intact actin cytoskeleton. Although we focus on basic cell cycle questions in yeast, our techniques are suitable for most nonadherent cells and subcellular particles to characterize cell growth in a variety of applications.biosensor | cell growth | cell size | microfluidics | Saccharomyces

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Section: Resultsmentioning

confidence: 96%

Measurement of mass, density, and volume during the cell cycle of yeast

Bryan

Goranov²,

Amon³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

254

192

View full text Add to dashboard Cite

show abstract

“…Though this technique does not allow accurate quantifications, it is used here for a rough estimation that showed that PCD is a highly abundant protein that makes between 5 and 10% of the total soluble protein. The following assumptions were taken into account to estimate the cellular PCD concentration in ‘ A. aromaticum ’: (i) density of a standard Gram‐negative cell is 1.1 g ml −1 (Baldwin et al ., ), (ii) dry mass of cells is 30% of wet mass, (iii) protein accounts for ≈ 50% of dry mass, (iv) soluble protein is ≈80% of total protein and (v) PCD makes 7.5% of soluble protein. Using these numbers 1 mg of cells (wet mass) contained approximately 9 mg PCD.…”

Section: Resultsmentioning

confidence: 99%

Evolution of a xenobiotic degradation pathway: formation and capture of the labile phthaloyl‐CoA intermediate during anaerobic phthalate degradation

Mergelsberg

Egle

Boll

2018

Molecular Microbiology

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Xenobiotic phthalates are industrially produced on the annual million ton scale. The oxygen-independent enzymatic reactions involved in anaerobic phthalate degradation have only recently been elucidated. In vitro assays suggested that phthalate is first activated to phthaloyl-CoA followed by decarboxylation to benzoyl-CoA. Here, we report the heterologous production and characterization of the enzyme initiating anaerobic phthalate degradation from 'Aromatoleum aromaticum': a highly specific succinyl-CoA:phthalate CoA transferase (SPT, class III CoA transferase). Phthaloyl-CoA formed by SPT accumulated only to sub-micromolar concentrations due to the extreme lability of the product towards intramolecular substitution with a half-life of around 7 min. Upon addition of excess phthaloyl-CoA decarboxylase (PCD), the combined activity of both enzymes was drastically shifted towards physiologically relevant benzoyl-CoA formation. In conclusion, a massive overproduction of PCD in phthalate-grown cells to concentrations >140 μM was observed that allowed for efficient phthaloyl-CoA conversion at concentrations 250-fold below the apparent K -value of PCD. The results obtained provide insights into an only recently evolved xenobiotic degradation pathway where a massive cellular overproduction of PCD compensates for the formation of the probably most unstable CoA ester intermediate in biology.

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“…These factors include differences in bacterial species (36), bacterial strains (22,30), type of intracytoplasmic membranes in methanotrophic bacteria (33), composition (22) and osmolarity (2,3,4) of the growth medium, hyperosmotic shock (5), mutation causing overproduction of proline (1), antibiotic (␤-lactam) resistance mutation (8), presence of capsule (28), growth rate (38), degradation of DNA and RNA (30), cell size (31), and the phase of the cell division cycle (11). Further elaborate biochemical work will be required to clarify which factors are involved in the change of buoyant density under the present experimental conditions.…”

Section: Discussionmentioning

confidence: 99%

Density-Dependent Sorting of Physiologically Different Cells of Vibrio parahaemolyticus

Nishino

Nayak

Kogure

2003

Appl Environ Microbiol

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A pure bacterial culture is composed of clonal cells in different physiological states. Separation of those subpopulations is critical for further characterization and for understanding various processes in the cultured cells. We used density-dependent cell sorting with Percoll to separate subpopulations from cultures of a marine bacterium, Vibrio parahaemolyticus. Cells from cultures in the exponential and stationary phases were fractionated according to their buoyant density, and their culturability and ability to maintain culturability under low-temperature and low-nutrient stress (stress resistance) were determined. The buoyant density of the major portion of the cells decreased with culture age. The culturability of stationary-phase cells increased with increasing buoyant density, but that of exponential-phase cells did not. Stress resistance decreased with increasing buoyant density regardless of the growth phase. The results indicate that density-dependent cell sorting is useful for separating subpopulations of different culturabilities and stress resistances. We expect that this method will be a powerful tool for analyzing cells in various physiological states, such as the viable but nonculturable state.A bacterial culture started from one colony is a clonal population. This, however, does not mean that all the cells behave identically (20,23). The presence of subpopulations with different physiological and morphological characteristics is known, especially among cells in the stationary phase of culture (16). Recent studies indicate that the cell's physiological states are controlled by a set of genes specifically expressed in various growth phases (16,17,25,35).The presence of subpopulations is also expected for cells in the viable but nonculturable state (10, 39). It is commonly observed that when bacterial cells are transferred from rich to poor medium, some cells start losing culturability, although they still show certain metabolic activities (19,26). Entry into the viable but nonculturable state is dependent on the cellular growth phase or physiological state. In general, cells in stationary phase or those experiencing stress conditions tend to retain culturability longer (18,27). In a culture entering the viable but nonculturable state, there may be at least three subpopulations, that is, cells retaining culturability, cells lacking culturability but retaining metabolic activity (i.e., viable but nonculturable state), and cells showing no detectable biological activity. Because they coexist in one batch culture, the separation of cells in the viable but nonculturable state from other subpopulations is critical for further detailed investigations. However, currently no simple, reliable method is available for this purpose.Density-gradient centrifugation is a useful technique for separating cells or organelles of different densities. In bacteriology, this technique has been applied to separation of cells in different stage of the cell cycle (6, 13, 15, 31), separation of competent cells for transfor...

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Buoyant density of Escherichia coli is determined solely by the osmolarity of the culture medium

Cited by 28 publications

References 8 publications

Measurement of mass, density, and volume during the cell cycle of yeast

Measurement of mass, density, and volume during the cell cycle of yeast

Evolution of a xenobiotic degradation pathway: formation and capture of the labile phthaloyl‐CoA intermediate during anaerobic phthalate degradation

Density-Dependent Sorting of Physiologically Different Cells of Vibrio parahaemolyticus

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