A mesoscopic stochastic model for the specific consumption rate in substrate-limited microbial growth

• Published in: PloS one Vol. 12; no. 2; p. e0171717
• Main Authors: Arranz, F J, Peinado, J M
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 10.02.2017; Public Library of Science (PLoS)
• Subjects: Bacteria - growth & development; Bacteria - metabolism; Bacterial Physiological Phenomena; Biological effects; Biology and Life Sciences; Carbohydrate Metabolism; Carbon; Cell Proliferation; Enzymes; Growth rate; Kinetics; Microbial growth; Microorganisms; Models, Theoretical; Physical Sciences; Probability distribution functions; Protein transport; Proteins; Reaction kinetics; Research and Analysis Methods; Saccharomyces cerevisiae; Stochastic models; Stochastic Processes; Stochasticity; Substrates; Transport; Transport proteins; Spain
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0171717

The specific consumption rate of substrate, as well as the associated specific growth rate, is an essential parameter in the mathematical description of substrate-limited microbial growth. In this paper we develop a completely new kinetic model of substrate transport, based on recent knowledge on the structural biology of transport proteins, which correctly describes very accurate experimental results at near-zero substrate concentration values found in the literature, where the widespread Michaelis-Menten model fails. Additionally, our model converges asymptotically to Michaelis-Menten predictions as substrate concentration increases. Instead of the single active site enzymatic reaction of Michaelis-Menten type, the proposed model assumes a multi-site kinetics, simplified as an apparent all-or-none mechanism for the transport, which is controlled by means of the local substrate concentration in the close vicinity of the transport protein. Besides, the model also assumes that this local concentration is not equal to the mean substrate concentration experimentally determined in the culture medium. Instead, we propose that it fluctuates with a mostly exponential distribution of Weibull type.