Microbial Growth Kinetics

Bioprocess, Bioseparation, and Cell Technology, 2009

Critical Reviews in Food Science and Nutrition, 2011

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Journal of Biological Physics, 1990

The growth rates of aspergillus, fusarium, and penicillium microorganism colonies in 'Czapex Dox Agar' as a feed material, under room conditions, are observed to be linear. This phenomenon is mathematically modeled and exactly predicted on the basis of the exponential growth assumption of a single microorganism. The approach allows an easy determination of the multiplication constant of a 'had microorganisms been allowed to grow freely' microorganism, in given conditions.

2004

The aim of this study was to evaluate the suitability of several mathematical functions for describing microbial growth curves. The nonlinear functions used were: three-phase linear, logistic, Gompertz, Von Bertalanffy, Richards, Morgan, Weibull, France and Baranyi. Two data sets were used, one comprising 21 growth curves of different bacterial and fungal species in which growth was expressed as optical density units, and one comprising 34 curves of colony forming units counted on plates of Yersinia enterocolitica grown under different conditions of pH, temperature and CO 2 (time-constant conditions for each culture). For both sets, curves were selected to provide a wide variety of shapes with different growth rates and lag times. Statistical criteria used to evaluate model performance were analysis of residuals (residual distribution, bias factor and serial correlation) and goodness-of-fit (residual mean square, accuracy factor, extra residual variance F-test, and Akaike's information criterion). The models showing the best overall performance were the Baranyi, three-phase linear, Richards and Weibull models. The goodness-of-fit attained with other models can be considered acceptable, but not as good as that reached with the best four models. Overall, the Baranyi model showed the best behaviour for the growth curves studied according to a variety of criteria. The Richards model was the best-fitting optical density data, whereas the three-phase linear showed some limitations when fitting these curves, despite its consistent performance when fitting plate counts. Our results indicate that the common use of the Gompertz model to describe microbial growth should be reconsidered critically, as the Baranyi, three-phase linear, Richards and Weibull models showed a significantly superior ability to fit experimental data than the extensively used Gompertz.

2012

Human beings have exploited the catalytic abilities of microorganisms for millennia, although it was not consciously until the discovery of microorganisms and enzymes. Since then, the number of products and services using microorganisms has multiplied geometrically. It is quite clear to us now that cells possess tremendous catalytic activities, as life can thrive in almost every corner of our planet, often forming consortia for degrading substances that hardly could be considered as substrates for life. These amazing capabilities make microorganisms and other cultured cells powerful catalyst that can be exploited just as they are found in nature or even improved by modifying their physiology. At the middle of the 20 century, changes in the physiology of cells were produced by mutation, a cluttered chaotic process that required lots of experimentation; latter on, by the 1970’s, recombinant DNA technologies gave birth to the so called “genetic engineering”, by which specific genes are...

RAS Microbiology and Infectious Diseases, 2021

An empirical model describes the behavior of an ideal microbial culture that mimics the real one. The predicted growth curve, log[N(t)], includes the onset tail of the observed sigmoid trend, while the latency phase that precedes the cell duplication is a time gap, which does not coincide with the so-called lag phase of other models. Unsolved remains the issue of the time scale: does the origin of the time scale of the experimenter coincide with that of the microbial culture? The correlation between duration of latency phase and maximum slope of the growth trend allows determination of a “true” starting point of the growth progress as the origin of the time scale of the microbial culture. Rigid shifts in the time scale of the experimenter allow alignment of the growth trends of real microbial cultures (in excess substrate, in the same medium and at the same temperature), no matter the starting population density. The time scale of the bacterial culture allows a consistent evaluation...

Biotechnology and Bioengineering, 1976

One of the main criticisms to the current chemostat theory is that it uses a first order rate expression to describe the microbial growth taking place in the vessel. This rate equation is

Journal of Life Sciences, 2013

Understanding microbial growth is essential to any research conducted in the fields of microbiology and biotechnology. Current methods of determining growth characteristics of microbes involve subjective graphical interpretations of linearized logarithmic data. Reducing error in logistical data decreases disparity between graphical and analytical predictions of microbial characteristics. In this study, a method has been developed to calculate the kinetics of microbial characteristics utilizing a modified Maclaurin series. Convergence of this series approaches the true kinetic value of microbial characteristics to include specific growth rates. In this research, a modified Maclaurin series is used to evaluate microbial kinetics in comparison to graphical determinations.

Mathematics and Computers in Simulation, 1996