PHOSPHATE-LIMITED GROWTH OF PAVLOVA LUTHERI (PRYMNESIOPHYCEAE) IN CONTINUOUS CULTURE: DETERMINATION OF GROWTH-RATE-LIMITING SUBSTRATE CONCENTRATIONS WITH A SENSITIVE BIOASSAY PROCEDURE1

2011 ◽  
Vol 47 (5) ◽  
pp. 1089-1097 ◽  
Author(s):  
Edward A. Laws ◽  
Shaofeng Pei ◽  
Paul Bienfang ◽  
Scott Grant ◽  
William G. Sunda
Keyword(s):  
Growth Rate ◽  
Continuous Culture ◽  
Limited Growth ◽  
Pavlova Lutheri ◽  
Rate Limiting ◽  
Substrate Concentrations

Effects of vitamin B12 concentration on chemostat cultured Synechococcus sp. strain PCC 7002

1995 ◽  
Vol 41 (2) ◽  
pp. 145-151 ◽  
Author(s):  
Steven W. Wilhelm ◽  
Charles G. Trick
Keyword(s):  
Growth Rate ◽  
Vitamin B12 ◽  
Continuous Culture ◽  
Gel Electrophoresis ◽  
Outer Membrane Proteins ◽  
Polyacrylamide Gel Electrophoresis ◽  
Entire Group ◽  
Vitamin B ◽  
Limited Growth ◽  
Synechococcus Sp

The effects of vitamin B12 availability on the physiology of the cyanobacterium Synechococcus sp. strain PCC 7002 were examined in a continuous culture chemostat system. The availability of vitamin B12 within the system was demonstrated to control the cell density and cellular chlorophyll levels under nutrient-limiting conditions. Electron micrographs of vitamin B12 replete and vitamin B12 deficient cyanobacteria indicated that a reduction in vitamin B12 availability induced a loss of thylakoid integrity within the system. Polyacrylamide gel electrophoresis demonstrated that the expression of outer membrane proteins of 95, 70, and 34 kDa was enhanced during vitamin B12 limited growth. Cellular quotients were determined to be a minimum of 256 molecules of vitamin B12/cell to sustain a growth rate of 0.6/day. A comparison with eukaryotic plankton demonstrated that the vitamin B12 requirements of cyanobacteria may be more similar to those of chloroplasts than to those of the entire group of eukaryotic algae.Key words: chemostats, cellular quotients, cyanobacterial physiology, Synechococcus, vitamin B12.

Influence of light on microalgae growth in continuous culture of low density

2019 ◽  
pp. 1-7 ◽  
Author(s):  
Rudolf P. Trenkenshu
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Continuous Culture ◽  
Specific Growth ◽  
Dark Phase ◽  
Low Density ◽  
Structural Components ◽  
Limited Growth ◽  
Linear Splines ◽  
Microalgae Growth

A mathematical model of the dependence of the specific growth rate of microalgae on the light intensity for a continuous culture of low optical density is proposed. In the basis of the mechanism of light-limited growth is the thesis on photosynthesis having light and dark phases. The product of the first phase is carbohydrates, which are used in the dark phase as a source of energy and carbon skeletons for the synthesis of all structural components of cells .Rates of the processes are described by linear splines. The equations describing the dependence of the specific growth rate on the intensity of the acting light are obtained.

Oscillating conditions for influencing the composition of mixed biological cultures

1998 ◽  
Vol 37 (4-5) ◽  
pp. 259-262 ◽  
Author(s):  
Bjarne R. Horntvedt ◽  
Morten Rambekk ◽  
Rune Bakke
Keyword(s):  
Growth Rate ◽  
Specific Growth ◽  
Heterotrophic Bacteria ◽  
Bacterial Species ◽  
Rate Reduction ◽  
Similar Strategy ◽  
Sinusoidal Oscillations ◽  
Specific Growth Rates ◽  
Rate Limiting ◽  
Concentration Levels

This paper presents a strategy in which mixed biological cultures are exposed to oscillating concentration levels, to improve the potential for coexistence of desired bacterial species. A mechanistic mathematical model is constructed to investigate and illustrate this strategy. This paper is focused on competition between nitrifying, denitrifying and aerobic heterotrophic bacteria in a CSTR with sludge recycle. For nitrifying and aerobic heterotrophic cultures, the effect of sinusoidal oscillations in DO levels with an amplitude of 1.0 mg/l is a 16% specific growth rate reduction compared to that at a constant DO level. The denitrifiers growth rate is increased by an average of 59%, compared to the constant DO level situation. A similar strategy has been tested in a pilot plant. It is concluded that the influence on specific growth rates is a function of the amplitude of the oscillations. The effects are greatest when concentrations fluctuate around the half saturation concentration of the rate limiting component(s).

CONTINUOUS CULTURE OF BRUCELLA ABORTUS S.19

1961 ◽  
Vol 7 (4) ◽  
pp. 491-505 ◽  
Author(s):  
Andreas H. W. Hauschild ◽  
Hilliard Pivnick
Keyword(s):  
Growth Rate ◽  
Continuous Culture ◽  
Dilution Rate ◽  
Brucella Abortus ◽  
Specific Growth ◽  
Limiting Factor ◽  
Continuous Growth ◽  
Viable Cells ◽  
Metabolic Products ◽  
Growth Of Bacteria

An apparatus is described for the continuous growth of bacteria. Brucella abortus S.19 has been grown in continuous culture for periods up to 3 weeks with populations up to 2 × 1011viable cells per ml and without the establishment of nonsmooth variants.Concentrations between 3 × 109and 2 × 1011cells per ml could be maintained as a function of the dilution rate without the requirement of a known limiting factor in the medium. In a series of steady-state conditions, the specific growth rate increased steadily up to 0.28 hour−1with decreasing population levels.Incidence of mutants was governed by the dilution rate and could also be reduced by various chelating substances.In continuous growth combined with continuous dialysis, population levels were approximately twice those obtained in continuous growth without dialysis. The effect of dialysis appears to be the continuous removal of growth-limiting metabolic products.

Inhibition of carbon fixation as a function of zinc uptake in natural phytoplankton assemblages

1979 ◽  
Vol 59 (4) ◽  
pp. 937-949 ◽  
Author(s):  
Anthony G. Davies ◽  
Jillian A. Sleep
Keyword(s):  
Carbon Fixation ◽  
Natural Populations ◽  
Plant Cells ◽  
Toxic Metal ◽  
Vitamin B ◽  
Phytoplankton Assemblages ◽  
Metal Contents ◽  
Rate Limiting ◽  
Natural Phytoplankton

There is now a substantial body of evidence that the growth rates of phytoplankton in culture are more closely related to the cellular levels of the rate-limiting constituent, be it a nutrient, micronutrient or toxic metal, than to the concentrations in the supporting medium; nitrate, Caperon (1968); phosphate, Fuhs (1969); silicate, Paasche (1973); vitamin B12, Droop (1968); iron, Davies (1970); mercury, Davies (1974); cadmium, Davies (1978a). This has suggested the requirement for a technique which would allow the determination of comparable relationships for natural populations of phytoplankton - how, for instance, their carbon fixation rates depend upon the metal contents of the plant cells. Although the effects of metals upon carbon fixation in phytoplankton assemblages from several different sea areas have already been examined (Knauer & Martin, 1972; Patin et al. 1974; Zingmark & Miller, 1975; Ibragim & Patin, 1976) no data seem to have been obtained on the levels of the metals present in the phytoplankton at the time of the measurements.

scholarly journals The determination of binding parameters when the total and free substrate concentrations are not approximately equal

1979 ◽  
Vol 179 (3) ◽  
pp. 697-700 ◽  
Author(s):  
N Gains
Keyword(s):  
Substrate Concentration ◽  
Graphical Method ◽  
Enzyme Concentration ◽  
Binding Parameters ◽  
Free Concentration ◽  
Equilibrium Binding ◽  
Substrate Concentrations

By using a standard graphical method values of Km and V may be found that are independent of the conditions and assumptions that the total substrate concentration approximates to its free concentration and that Km is much larger than the enzyme concentration. The procedure is also applicable to the determination of equilibrium binding parameters of a ligand to a macromolecule.

Freezing in Silicon at Large Undercooling

1989 ◽  
Vol 157 ◽  
Author(s):  
P.A. Stolk ◽  
A. Polman ◽  
W.C. Sinke
Keyword(s):  
Interface Temperature ◽  
Limiting Factor ◽  
Time Resolved ◽  
Large Undercooling ◽  
Explosive Crystallization ◽  
Crystallization Speed ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Rate Limiting

ABSTRACTPulsed laser irradiation is used to induce epitaxial explosive crystallization of amorphous silicon layers buried in a (100) oriented crystalline matrix. This process is mediated by a self-propagating liquid layer. Time-resolved determination of the crystallization speed combined with numerical calculation of the interface temperature shows that freezing in silicon saturates at 16 m/s for large undercooling (> 130 K). A comparison between data and different models for melting and freezing indicates that the crystallization behavior at large undercooling can be described correctly if the rate-limiting factor is assumed to be diffusion in liquid Si at the solid/liquid interface.

Determination of the Growth Rate of Hydrothermally Synthesised ZnO2 Crystallites

2017 ◽  
Vol 50 ◽  
pp. 41-47 ◽  
Author(s):  
Martin Egblewogbe ◽  
Garu Gebreyesus ◽  
Samuel A. Atarah
Keyword(s):  
Growth Rate ◽  
Zinc Acetate Dihydrate ◽  
Hydrothermal Process ◽  
Growth Rate Constant ◽  
Acetate Dihydrate ◽  
X Ray ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Zinc Peroxide

Powders consisting of nanoparticles of zinc peroxide were prepared via a simple hydrothermal process using zinc acetate dihydrate and hydrogen peroxide precursors. The size of the crystallites was determined using x-ray powder diffraction. Over a period of 5 hours the crystallite radius increased from 4 nm – 9 nm at a temperature of 68 °C ± 5 °C, with growth rate constant of 0.23 nm3 min−1 calculated using the Lifshitz, Slyozov, and Wagner model. The powders were further characterised with High Resolution Transmission Electron Microscopy, Energy Dispersive X-ray analysis, and Small Angle X-ray Scattering, showing well-crystallised ZnO2 nanoparticles.

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