The Growth of Bacteria with a Constant Food Supply

Jordan, R. C.; Jacobs, S. E.; Sims, A L

doi:10.1128/jb.48.5.579-598.1944

Cited by 24 publications

(3 citation statements)

References 13 publications

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“…In Graham-Smith's media, however, dilution from 2 to 10 times caused a similar reduction in viable count. Analogous results have been more recently obtained in carefully controlled quantitative experiments by Jordan & Jacobs (1944), but in Bail's examples there is still some unknown limitation to the survival of living bacteria. That this limiting factor is not the accumulation of toxic material is shown by the regrowth of organisms when they are removed by centrifugalization.…”

Section: Introduction and Historicalsupporting

confidence: 73%

The growth of bacterial colonies and their viable population

Mayr‐Harting

1947

J. Hyg.

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Section: Introduction and Historicalsupporting

confidence: 73%

The growth of bacterial colonies and their viable population

Mayr‐Harting

1947

J. Hyg.

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“…If each cell divides into two daughter cells and the process is repeated continuously, then if a and b are the numbers at the beginning and end of a time period t , the number of generation periods, n, will be equal to (log b-log a)/log 2 and the generation time, G, equal to t/n. Wilson (1922) and Jordan & Jacobs (1944), however, demonstrated an excess of total over viable organisms , and Wilson (1922) showed that with broth cultures of Bacterium suipestifer (Salmonella cholerae-suis), a factor of 1.71 should be substituted for 2 in the above equation. This factor is the generation index, P, and corresponds to the mean proportion of viable cells produced in one generation by a unit number of parent cells.…”

Section: Discussionmentioning

confidence: 99%

The Influence of Temperature on the Effect of Bacteriostatic Concentrations of Phenol Against Escherichia coli

Parkinson

Pickett

1964

Journal of Applied Bacteriology

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Summary. During early exponential growth of Escherichia coli in the absence of phenol there is a natural death rate at 20, 30, and 44° but at the optimum temperature around 37° there is little if any significant death. The influence of a rise in temperature from 20 to 44° is to decrease the generation time and at 44° the lower generation time compensates for a reduced generation index. The main effect of sub‐bacteriostatic concentrations of phenol is to increase the generation time but at 30, 37 and 44° there is a significant reduction in the generation index at the higher concentrations resulting in a dynamic bacteriostasis. At 20° bacteriostasis is due mainly to a large generation time but there is a little growth and so bacteriostasis is essentially dynamic. There is also evidence to suggest that the effect of a particular concentration of phenol on the generation index is not merely influenced by the temperature but by the generation time under the particular set of conditions. If phenol is added to rapidly growing cultures of E. coli the effect of a rise in temperature is to reduce the concentration required for bacteriostasis but if it is added during the lag phase there is a maximum in the bacteriostatic concentration between 20 and 37°.

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“…Under these conditions of controlled pH, aeration and food supply at 350 C., the viable population of the culture rose within a few hours to approximately 330 million cells per ml., at which level the viable count remained constant as long as the food addition was continued, as shown by Jordan & Jacobs (1944b). The population level was in fact controlled by the rate of food addition.…”

Section: Methodsmentioning

confidence: 92%

Studies in the dynamics of disinfection. XI. The effect of lethal temperatures on standard cultures ofBact. coli. IV. An investigation of that portion of the population which survives prolonged exposure atpH 7·0

Jordan

Jacobs

Davies

1947

J. Hyg.

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1. An attempt has been made to discover the origin and nature of the small proportion of the cells in standard cultures ofBact. coliwhich is able to withstand, apparently indefinitely, exposure to temperatures of 49, 51 and 53° C.2. The method adopted was to allow these survivors to generate fresh cultures in the same flask merely by reducing the temperature to 35° C. and to subject the resulting cultures in turn to heat treatment. Only one process of regeneration and subsequent disinfection was carried out at 49 and 53° C., but at 51° C. the process was repeated four times. The disinfection curve was determined on each occasion and the permanent population allowed to become established.3. Changes in the heat resistance of the cultures were judged by (a) the disinfection times (99·99 % mortality), (b) the maximum death-rates, (c) the levels of the surviving populations and (d) the variations in death-rate with time during each disinfection.4. Marked fluctuation in numbers of viable cells was observed during each of the phases of permanent surviving population. The exact levels of survivors were therefore uncertain, but after exposure to 49° C. the mean values were not higher than when 53° C. was used, nor was there an increase in the mean numbers of survivors in the successively regenerated cultures.5. The survivors did not grow when inoculated into either nutrient agar plates or tubes of broth held at the respective high temperatures, although they remained alive and developed readily on being transferred to 35° C.6. The maximum death-rate decreased and the disinfection time increased markedly after one regeneration of the cultures. The increase in the latter was not wholly due to the decrease in the former, as the death-rates throughout the disinfection of the regenerated culture were lower.7. After the second regeneration (at 51° C.) the maximum death-rate declined and the disinfection time rose still higher, but the process was reversed after the third and fourth regenerations.8. The shape of the graph of log survivors against time altered markedly after the second regeneration at 51° C. The initial death-rate was higher but fell sharply to a minimum before rising again to the final maximum.9. The experimental findings are discussed. An increase in the general heat resistance of these cultures may have occurred as a result of one regeneration, but the technique employed permitted the gradual alteration of the environmental conditions, and this appears to have exerted complex effects on the cultures so that the results of further regenerations are inconclusive.

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The Growth of Bacteria with a Constant Food Supply

Cited by 24 publications

References 13 publications

The growth of bacterial colonies and their viable population

The growth of bacterial colonies and their viable population

The Influence of Temperature on the Effect of Bacteriostatic Concentrations of Phenol Against Escherichia coli

Studies in the dynamics of disinfection. XI. The effect of lethal temperatures on standard cultures ofBact. coli. IV. An investigation of that portion of the population which survives prolonged exposure atpH 7·0

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