Modelling the growth rate of Escherichia coli as a function of pH and lactic acid concentration.

1997 ◽  
Vol 63 (6) ◽  
pp. 2355-2360 ◽  
Author(s):  
K A Presser ◽  
D A Ratkowsky ◽  
T Ross
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Lactic Acid ◽  
Acid Concentration ◽  
Lactic Acid Concentration

scholarly journals Modelling the Growth Limits (Growth/No Growth Interface) of Escherichia coli as a Function of Temperature, pH, Lactic Acid Concentration, and Water Activity

1998 ◽  
Vol 64 (5) ◽  
pp. 1773-1779 ◽  
Author(s):  
K. A. Presser ◽  
T. Ross ◽  
D. A. Ratkowsky
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Water Activity ◽  
Acid Concentration ◽  
Probability Model ◽  
Limiting Factors ◽  
Lactic Acid Concentration ◽  
Experimental Conditions ◽  
Growth Interface ◽  
Data Set

ABSTRACT The form of a previously developed Bělehr�dek type of growth rate model was used to develop a probability model for defining the growth/no growth interface as a function of temperature (10 to 37�C), pH (pH 2.8 to 6.9), lactic acid concentration (0 to 500 mM), and water activity (0.955 to 0.999; NaCl was used as the humectant).Escherichia coli was unable to grow in broth in which the undissociated lactic acid concentration exceeded 11 mM or, with two exceptions, at a pH of 3.9 or less with no lactic acid present. Under experimental conditions at which the pH and the undissociated acid concentrations were the major growth-limiting factors, the growth/no growth interface was essentially independent of temperature at temperatures ranging from 15 to 37�C. The interface between conditions that allowed growth and conditions at which growth did not occur was abrupt. The inhibitory effect of combinations of water activity and pH varied with temperature. Predictions of the model for the growth/no growth interface were consistent with 95% of the experimental data set.

scholarly journals Effect of lactic acid on the growth dynamics of Candida maltosa YP1

2011 ◽  
Vol 21 (No. 2) ◽  
pp. 43-49 ◽  
Author(s):  
D. Lauková ◽  
Ľ. Valík ◽  
F. Görner
Keyword(s):  
Growth Rate ◽  
Lactic Acid ◽  
Specific Growth Rate ◽  
Acid Concentration ◽  
Specific Growth ◽  
Glucose Solution ◽  
Growth Dynamics ◽  
Lag Phase ◽  
Lactic Acid Concentration ◽  
Candida Maltosa

The growth dynamics of the oxidative imperfect yeast strain Candida maltosa YP1 isolated from the surface of fruit yoghurt was studied in relation to the lactic acid concentration ranging from 0 to 1.6% (w/v). The maximal specific growth rate of 0.36 h<sup>&ndash;1</sup> and minimal lag-phase duration of 2.9 h were found in the glucose solution without lactic acid at 25&deg;C. The decrease of the natural logarithm of both the specific growth rate (ln &micro;) and the lag-phase prolongation (ln ) in the dependence on the increase of lactic acid concentration (0&ndash;1.59%) was significantly linear (ln&nbsp;&micro; = &ndash;1.1458 &ndash; 0.6056 c; R<sup>2</sup><sub>(&micro;) </sub>= 0.9526; ln l = 1.0141 + 1.9766 c; R<sup>2</sup><sub>() </sub>= 0.9577). Based on these equations, the prediction of the time necessary for C. maltosa YP1 to reach 1 &times; 10<sup>6</sup> CFU/ml in the dependance on lactic acid concentration and, the initial density of the yeast culture was calculated. For example, C. maltosa YP1 was able to reach the level of 1 &times; 10<sup>6</sup> CFU/ml in a model glucose solution at the initial concentration N<sub>0</sub> = 1 CFU/ml, 0.9% lactic acid and 25&deg;C within 2 d. The growth predictions presented indicate a considerable resistance of C. maltosa YP1 to lactic acid in the concentration of up to 1.3% (w/v). &nbsp;

Post-Mortem Diagnosis of Hypoxia by Means of Brain Lactic Acid Concentration

1958 ◽  
Vol 192 (3) ◽  
pp. 577-580 ◽  
Author(s):  
Donald D. Van Fossan ◽  
Robert T. Clark
Keyword(s):  
Lactic Acid ◽  
Acid Concentration ◽  
Oxygen Deficiency ◽  
Postmortem Brain ◽  
Post Mortem ◽  
Lactic Acid Concentration ◽  
Altitude Exposure ◽  
Post Mortem Brain ◽  
Exposure Levels ◽  
The Brain

Simulated altitude exposure elevates the postmortem brain lactic acid concentration up to 98 mg/100 gm above controls depending on species used, duration, and intensity of exposure. The sharp difference in post-mortem brain lactic acid concentration between altitude exposed animals and controls remains demonstrable for the longest postmortem intervals studied (20 hr. in the dog, 30 hr. in the rabbit, and 6 hr. in the rat). Upon recovery from altitude exposure the brain lactic acid and/or precursors return toward pre-exposure levels in accordance with first order reaction kinetics during the first few minutes. The velocity constant is .32 and the half-life is 2.2 minutes. Elevated post-mortem brain lactic acid concentration is a constant finding in animals which were hypoxic at the time of death and appears to be a suitable criterion for establishing ante-mortem altitude exposure or other physiologically similar oxygen deficiency situations.

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