Growth efficiency as a cellular objective in Eschericia coli

Feb 23, 2011, 1:30 PM
FB52 (a)




Olli Yli-Harja (Tampere University of Technology)


Tommi Aho (1), Juha Kesseli (1), Olli Yli-Harja (1), Stuart A. Kauffman (2)
(1) Department of Signal Processing, Tampere University of Technology, Korkeakoulunkatu 1, 33720 Tampere, Finland
(2) Complex Systems Center, University of Vermont, U.S.A
The shortage of nutrients is one of the most common challenges that organisms confront. Thus, nature has developed various highly efficient systems for processing nutrients, e.g. enzymes that efficiently transform substrates to products. Here, we study transformation efficiency in another level, namely in bacterial metabolism. We use a metabolic model of Eschericia coli to examine growth efficiency, i.e. the transformation efficiency of substrates to new biomass. We find that under the common assumption of maximal growth, the growth efficiency remains sub-optimal. We find that in the E. coli model the maximal growth efficiency is obtained at a finite nutrient uptake rate. We examine whether the growth efficiency could serve as the cellular objective in metabolic modeling, and find that cellular growth can be predicted reasonably well under this assumption.
Maximal growth efficiency is a plausible candidate as the cellular objective under the examined cultivation conditions in E. coli. Transformation efficiency in general could be studied as a functional design principle of cellular systems.

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