Facultad EMPRESARIALES

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Model checking is a well known method to carry out formal verification of distributed systems. This method needs a model representing the behaviour of the system to be verified. The size of this model depends on the complexity of the system. To be able to verify real life systems, it is necessary to use techniques allowing to take advantage of all the available storage space, to reduce the amount of information needed for the verification and to speed up computation time. But the expressiveness of the languages used to describe the system and its expected behaviours (properties) limit the possible reductions. We present in this paper our choices for an automatic verification tool by using model checking. The preliminary results obtained from its use for the verification of a real life protocol allow us to make some estimations about the limits of model checking methods.

Genetic engineering of metabolic pathways is a standard strategy to increase the production of metabolites of economic interest. However, such flux increases could very likely lead to undesirable changes in metabolite concentrations, producing deleterious perturbations on other cellular processes. These negative effects could be avoided by implementing a balanced increase of enzyme concentrations according to the Universal Method [Kacser and Acerenza (1993) Eur J Biochem 216:361–367]. Exact application of the method usually requires modification of many reactions, which is difficult to achieve in practice. Here, improvement of threonine production via pyruvate kinase deletion in Escherichia coli is used as a case study to demonstrate a partial application of the Universal Method, which includes performing sensitivity analysis. Our analysis predicts that manipulating a few reactions is sufficient to obtain an important increase in threonine production without major perturbations of metabolite concentrations. Biotechnol. Bioeng. 2009;103: 609–620. © 2009 Wiley Periodicals, Inc.