Experimental and theoretical analysis of poly(β-hydroxybutyrate) formation and consumption in Ralstonia eutropha

In this paper a mathematical model is presented to describe poly(β-hydroxybutyrate) (PHB) formation and consumption in Ralstonia eutropha. The model is based on the hybrid cybernetic modeling approach, which was introduced by Kim et al. [1] and which allows a systematic derivation of the model equations from elementary mode analysis. An extension of this approach is presented to allow for non quasi-stationary metabolites, i.e. PHB. The model is shown to be in good agreement with experimental data for PHB formation and consumption. The model is used afterwards to discuss the occurrence of multiple steady states in a continuous bio reactor. It is shown that the multiplicity region predicted by the model is rather small and it is argued that multiple steady states are therefore unlikely to occur in practice for this specific system.Due to various desirable features such as accounting for cellular regulation at network level and dynamics of intracellular metabolites with a moderate complexity, it is believed that the constructed model is most suitable for control, optimization and monitoring of industrial PHB production processes.

► We model PHB degradation as well as consumption in R. eutropha.
► We extended the HCM approach to take internal metabolites explicitly into account.
► Possibility of multiple steady states in continuous bio reactor were investigated.
► Influence of PHB consumption is analyzed and found to be crucial at low dilution rate.