Optimal management of nutrient reserves in microorganisms under time-varying environmental conditions
van den Berg, HA
Journal of Theoretical Biology
© 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
Reason for embargo
Under embargo until 23/06/2018 in compliance with publisher policy.
Intracellular reserves are a conspicuous feature of many bacteria; such internal stores are often present in the form of inclusions in which polymeric storage compounds are accumulated. Such reserves tend to increase in times of plenty and be used up in times of scarcity. Mathematical models that describe the dynamical nature of reserve build-up and use are known as “cell quota,” “dynamic energy/nutrient budget,” or “variable-internal-stores” models. Here we present a stoichiometrically consistent macro-chemical model that accounts for variable stores as well as adaptive allocation of building blocks to various types of catalytic machinery. The model posits feedback loops linking expression of assimilatory machinery to reserve density. The precise form of the “regulatory law” at the heart of such a loop expresses how the cell manages internal stores. We demonstrate how this “regulatory law” can be recovered from experimental data using several empirical data sets. We find that stores should be expected to be negligibly small in stable growth-sustaining environments, but prominent in environments characterised by marked fluctuations on time scales commensurate with the inherent dynamic time scale of the organismal system.
OAN was funded through EU Research Framework programme 7 Marie Curie Actions, grant 316630 Centre for Analytical Science – Innovative Doctoral Programme (CAS-IDP).
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.
Vol. 429, pp. 124 - 141