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

Lewis, Christina L.; Craig, Caelli C.; Senecal, Andre

doi:10.1128/aem.00117-14

Cited by 47 publications

(27 citation statements)

References 26 publications

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“…Cellular dry mass distributions of individual species followed a Gaussian-like distribution (Fig. 2) similar to previous observations on other bacterial species (35)(36)(37)(38).…”

Section: Resultssupporting

confidence: 87%

Direct Cell Mass Measurements Expand the Role of Small Microorganisms in Nature

Khachikyan

Milucka

Littmann

et al. 2019

Appl Environ Microbiol

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Microbial biomass is a key parameter needed for the quantification of microbial turnover rates and their contribution to the biogeochemical element cycles. However, estimates of microbial biomass rely on empirically derived mass-to-volume relationships, and large discrepancies exist between the available empirical conversion factors. Here we report a significant nonlinear relationship between carbon mass and cell volume (mcarbon=197×V0.46; R2=0.95) based on direct cell mass, volume, and elemental composition measurements of 12 prokaryotic species with average volumes between 0.011 and 0.705 μm3. The carbon mass density of our measured cells ranged from 250 to 1,800 fg of C μm−3 for the measured cell volumes. Compared to other currently used models, our relationship yielded up to 300% higher carbon mass values. A compilation of our and previously published data showed that cells with larger volumes (>0.5 μm3) display a constant (carbon) mass-to-volume ratio, whereas cells with volumes below 0.5 μm3 exhibit a nonlinear increase in (carbon) mass density with decreasing volume. Small microorganisms dominate marine and freshwater bacterioplankton as well as soils and marine and terrestrial subsurface. The application of our experimentally determined conversion factors will help to quantify the true contribution of these microorganisms to ecosystem functions and global microbial biomass. IMPORTANCE Microorganisms are a major component of Earth’s biosphere, and their activity significantly affects the biogeochemical cycling of bioavailable elements. To correctly determine the flux of carbon and energy in the environment, reliable estimates of microbial abundances and cellular carbon content are necessary. However, accurate assessments of cellular carbon content and dry weight are not trivial to obtain. Here we report direct measurements of cell dry and carbon mass of environmentally relevant prokaryotic microorganisms using a microfluidic mass sensor. We show a significant nonlinear relationship between carbon mass and cell volume and discuss this relationship in the light of currently used cellular mass models.

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“…Cellular dry mass distributions of individual species followed a Gaussian-like distribution (Fig. 2) similar to previous observations on other bacterial species (35)(36)(37)(38).…”

Section: Resultssupporting

confidence: 87%

Direct Cell Mass Measurements Expand the Role of Small Microorganisms in Nature

Khachikyan

Milucka

Littmann

et al. 2019

Appl Environ Microbiol

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“…For instance, an SPM of −359 kT for initial bacterial adhesion (Fig. B, APTES glass) could be overcome by bacterial cells (density 1.116 g mL −1 ) flowing at velocities greater than 4 cm s −1 . This value can also help in designing proper cleaning procedures by assessing necessary flow rates of cleaning agents and/or rinsing water.…”

Section: Discussionmentioning

confidence: 99%

Adhesion ofMegasphaera cerevisiaeonto solid surfaces mimicking materials used in breweries

et al. 2017

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Developments in filling technologies have led to a reduction in oxygen content in beer, thus producing an anaerobic environment suitable for the growth of anaerobic beer‐spoiling microorganisms. Anaerobic bacteria survive well in a biofilm that provides protection against environmental stress factors. The initial step in biofilm formation is adhesion of cells to a solid surface. Therefore the purpose of this research was to study theoretically and experimentally adhesion of strains of Megasphaera cerevisiae to different solid surfaces with properties covering a wide range of materials used in breweries. Experimental characterization of surface properties was used to model surface interactions, resulting in a quantitative prediction of cell adhesion. The colloidal model predictions were then compared with adhesion tests. As revealed experimentally, the most significant adhesion occurred to 3‐aminopropyltriethoxysilane‐modified glass (substitute for stainless steel) at pH 3–7. According to physicochemical interaction models, under these conditions interactions were influenced mostly by electrostatic attractions between surfaces. At pH 3, experimental data, supported by theoretical predictions, showed significant bacterial adhesion to borosilicate glass (a hydrophilic surface) and propyltriethoxysilane‐modified glass (a hydrophobic surface). Conversely, the least adhesion of M. cerevisiae was both predicted and observed at pH 10, since at an alkaline pH, electrostatic repulsion between surfaces predominates. Since adhesion can be expected mainly at an acidic pH, prevention should be based on the use of alkaline cleaning agents and/or alkaline rinse water at the end of the cleaning procedure. An elevated risk of adhesion to stainless steel was also identified, allowing appropriate measures to be taken. Copyright © 2017 The Institute of Brewing & Distilling

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“…4(c)-4(e)). In general, dead cells have less mass, 34 which should give them a higher velocity (v) according to the law of momentum conservation. However, the average velocity of the dead cells was 54% less than that of the living cells, suggesting that at least the mass of the particles was not a critical factor in reducing the stochastic parameters of the dead cells' random walk.…”

Section: -6mentioning

confidence: 99%

Characterization of anomalous movements of spherical living cells on a silicon dioxide glassy substrate

et al. 2015

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The random walk of spherical living cells on a silicon dioxide glassy substrate was studied experimentally and numerically. This random walk trajectory exhibited erratic dancing, which seemingly obeyed anomalous diffusion (i.e., Lévy-like walk) rather than normal diffusion. Moreover, the angular distribution (-π to π) of the cells' trajectory followed a "U-shaped pattern" in comparison to the uniform distribution seen in the movements of negatively charged polystyrene microspheres. These effects could be attributable to the homeostasis-driven structural resilient character of cells and physical interactions derived from temporarily retained nonspecific binding due to weak forces between the cells and substrates. Our results provide new insights into the stochastic behavior of mesoscopic biological particles with respect to structural properties and physical interactions.

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

Cited by 47 publications

References 26 publications

Direct Cell Mass Measurements Expand the Role of Small Microorganisms in Nature

Direct Cell Mass Measurements Expand the Role of Small Microorganisms in Nature

Adhesion ofMegasphaera cerevisiaeonto solid surfaces mimicking materials used in breweries

Characterization of anomalous movements of spherical living cells on a silicon dioxide glassy substrate

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