Electrokinetic Studies of Bacteria I: Effect of Nature, Ionic Strength, and pH of Buffer Solutions on Electrophoretic Mobility of Streptococcus faecalis and Escherichia coli

1972 ◽  
Vol 61 (2) ◽  
pp. 182-187 ◽  
Author(s):  
Hans Schott ◽  
C.Y. Young
Keyword(s):  
Escherichia Coli ◽  
Ionic Strength ◽  
Electrophoretic Mobility ◽  
Streptococcus Faecalis ◽  
Buffer Solutions

scholarly journals Reversal of Flagellar Rotation Is Important in Initial Attachment of Escherichia coli to Glass in a Dynamic System with High- and Low-Ionic-Strength Buffers

2002 ◽  
Vol 68 (3) ◽  
pp. 1280-1289 ◽  
Author(s):  
Jennifer W. McClaine ◽  
Roseanne M. Ford
Keyword(s):  
Escherichia Coli ◽  
Ionic Strength ◽  
Cell Attachment ◽  
Fluid Velocity ◽  
Soft Particle ◽  
Wild Type ◽  
Buffer Solutions ◽  
Fluid Velocities ◽  
Significant Difference ◽  
Flagellar Rotation

ABSTRACT The attachment rates of wild-type, smooth-swimming, tumbly, and paralyzed Escherichia coli to glass was measured at fluid velocities of 0.0044 and 0.044 cms−1 (corresponding to shear rates of 0.34 and 3.4 s−1, respectively), in 0.02 and 0.2 M buffer solutions. At the highest ionic strength, we did not observe a significant difference in the attachment rate of wild-type and paralyzed cells at either fluid velocity. However, when the ionic strength was reduced, paralyzed bacteria attached at rates 4 and 10 times lower than that of the wild type under fluid velocities of 0.0044 and 0.044 cms−1, respectively. This suggested that the rotation of the flagella assisted in attachment. We then compared the attachment rates of smooth-swimming (counterclockwise rotation only) and tumbly (clockwise rotation only) cells to the wild type to determine whether the direction of rotation was important to cell attachment. At 0.0044 cms−1, the smooth-swimming cells attached at rates similar to that of the wild type in both buffer solutions but significantly less at the higher fluid velocity. Tumbly cells attached at much lower rates under all conditions. Thus, the combination of clockwise and counterclockwise flagellar rotation and their coupling appeared to be important in cell attachment. We considered a number of hypotheses to interpret these observations, including a residence time analysis and a comparison of traditional Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to soft-particle theory.

Radiosensitization of Streptococcus faecalis and Escherichia coli

1964 ◽  
Vol 29 (1) ◽  
pp. 80-86 ◽  
Author(s):  
MOHAMED A. NOAMAN ◽  
GERALD J. SILVERMAN ◽  
NORMAN S. DAVIS ◽  
SAMUEL A. GOLDBLITH
Keyword(s):  
Escherichia Coli ◽  
Streptococcus Faecalis

Ethanol stability of casein micelles – a hypothesis concerning the role of calcium phosphate

1987 ◽  
Vol 54 (3) ◽  
pp. 389-395 ◽  
Author(s):  
David S. Horne
Keyword(s):  
Ionic Strength ◽  
Skim Milk ◽  
Buffer System ◽  
Casein Micelles ◽  
Buffer Solutions ◽  
Relative Response ◽  
Using Data ◽  
The Stability ◽  
Ethanol Stability

SummaryThe ethanol (EtOH) stability of skim milk and the stability towards aggregation of casein micelles diluted into ethanolic buffer solutions were compared using data obtained from previously published experiments. Differences in absolute stability and in relative response were observed when Ca2+ level and pH were adjusted, the buffer system results lying below those from skim milk in both cases. Increasing the ionic strength of skim milk adjusted to pH 7·0 lowered its EtOH stability whereas increasing the ionic strength of the diluting buffer increased the stability of the casein micelles. The hypothesis is put forward that the differences are due to the simultaneous precipitation of Ca phosphate when EtOH is added to skim milk. This draws calcium from the caseinate sites of the micelle, counteracting the destabilizing effects of the EtOH towards the micelle. Such removal and the consequent restructuring are kinetically controlled and micellar precipitation in skim milk finally occurs when the micellar coagulation time falls within the time scale of the restructuring reactions.

scholarly journals THE PROPERTIES OF MAMMALIAN STRIATED MYOFIBRILS ISOLATED BY AN ENZYMATIC METHOD

1950 ◽  
Vol 91 (6) ◽  
pp. 655-664 ◽  
Author(s):  
Armin F. Schick ◽  
George M. Hass
Keyword(s):  
Ionic Strength ◽  
Potassium Chloride ◽  
Phosphate Buffer ◽  
Phosphate Buffer Solution ◽  
Potassium Phosphate ◽  
Microscopic Structure ◽  
Buffer Solution ◽  
Buffer Solutions ◽  
Alkaline Side ◽  
Fresh Frozen

A new method for the isolation of large numbers of individual myofibrils from fresh mammalian skeletal and cardiac muscle has been described. Purification of isolated myofibrils was accomplished by differential centrifugation of fresh frozen sections of muscle which had been mechanically agitated after exposure for 30 to 45 minutes at 0°C. to the action of a dilute solution of trypsin in a phosphate buffer solution with a pH of 7.0 and an ionic strength of 0.25. Isolated skeletal myofibrils of the rabbit and man have similar constant solubility properties. They dissolve in an aqueous mixture of 0.5 N potassium chloride and 0.03 N sodium bicarbonate, giving viscous solutions which exhibit conspicuous birefringence of flow. They are soluble in buffer solutions (ionic strength 0.15) on the acid side of pH 4 and alkaline side of pH 10. If the ionic strength of potassium phosphate buffer solutions is increased to 0.5 or if the ionic strength of phosphate-borate buffer solutions is increased to a similar value by addition of potassium chloride, the isolated myofibrils become soluble at neutrality. Hence, it is possible, first to isolate the myofibrils and then dissolve them without deviating appreciably from physiologic ranges of pH. The extent to which myofibrils are modified by the conditions imposed by the method of isolation is unknown. There is no significant change in microscopic structure or optical birefringence. Furthermore, there is retention of a form of physiological reactivity, for when the isolated skeletal myofibrils are immersed in solutions of adenosinetriphosphate, they promptly and irreversibly change from elongated fibrils with distinct structural detail into dense spherical masses without recognizable microscopic structure.

Performance of Some Heat-Sensitive Differential Agars Prepared and Melted by Microwave Energy1

1988 ◽  
Vol 51 (7) ◽  
pp. 577-578 ◽  
Author(s):  
C. LIANG ◽  
D. Y. C. FUNG
Keyword(s):  
Escherichia Coli ◽  
Cell Count ◽  
Viable Cell ◽  
Microwave Energy ◽  
Microwave Oven ◽  
Viable Cell Count ◽  
Streptococcus Faecalis ◽  
Cell Counts ◽  
Significant Difference ◽  
Conventional Boiling

The viable cell count performance of some heat-sensitive differential agars prepared and remelted by microwave energy was evaluated for Salmonella choleraesui, Streptococcus faecalis and Escherichia coli. The conventional boiling method was used for comparison. No significant difference was found between the microwave oven processed agar and the conventional-boiling processed agar in viable cell counts of the target bacteria. Heating and reheating of violet red bile agar, bismuth sulfite agar, and KF Streptococcus agar by both methods did not change agar performance. However, remelting of desoxycholate citrate agar by both methods resulted in a substantial lowering of viable cell counts.

scholarly journals Buffer solutions in drug formulation and processing: How pKa values depend on temperature, pressure and ionic strength

2019 ◽  
Vol 560 ◽  
pp. 357-364 ◽  
Author(s):  
Lisa Samuelsen ◽  
René Holm ◽  
Audrey Lathuile ◽  
Christian Schönbeck
Keyword(s):  
Ionic Strength ◽  
Drug Formulation ◽  
Pka Values ◽  
Buffer Solutions

A Standard Test for Efficacy of Germicides and Acceptability of Residual Disinfecting Activity in Swimming Pool Water

1964 ◽  
Vol 47 (3) ◽  
pp. 540-547 ◽  
Author(s):  
L F Ortenzio ◽  
L S Stuart
Keyword(s):  
Escherichia Coli ◽  
Standard Test ◽  
Water Disinfection ◽  
Swimming Pool ◽  
Biological Test ◽  
Streptococcus Faecalis ◽  
Pool Water ◽  
Test Organisms ◽  
Swimming Pool Water

Abstract A biological test, using Escherichia coli and Streptococcus faecalis as test organisms, has been designed to determine the germicidal activity of water containing 0.4— 1.0 ppm of available chlorine at pH 7.0— 7.5. The few results presented clearly indicate the usefulness of the method in evaluating commercial disinfectant preparations recommended for use in swimming pool water disinfection. The procedure can be readily adapted to study the effects of chlorine stabilizers, the influence of various algaecides applied as adjuncts to water disinfectant on germicidal activity, and determinations as to the acceptability of residual disinfecting activity of swimming pool waters during times that the pool is in use.

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