Achim Kienle

Professor, Max Planck Institute for Dynamics of Complex Technical Systems and the Otto-von-Guericke University (OvGU) of Magdeburg




Hybrid Cybernetic Modeling of the Microbial Production of Polyhydroxyalkanoates Using Two Carbon Sources

Compared to conventional petroleum-based polymers, biopolymers like polyhydroxyalkanoates are a promising alternative as raw material for manufacturing of plastics. One way to reduce the microbial PHA production costs is to use organic wastes from agriculture and food industries, which contain a wide range of carbon sources. Two organic waste carbon sources are fructose, present in fruit juice waste and acetate, present in waste from wine or biogas production. Simulations using kinetic models can help to reduce the range of optimal substrate combinations and thus prevent time-consuming and costly experimental investigations.
This contribution outlines an extended hybrid cybernetic model for the polyhydroxybuyrate production in Cupriavidus necator growing on fructose, acetate, and nitrogen. Data from bioreactor experiments are used for the adjustment of the kinetic parameters and for the validation of the hybrid cybernetic model. The new model is able to precisely predict the dynamic behaviour of hydroxybutyrate while co-feeding with fructose and acetate. Finally, our model is used in a computational study to analyze different initial carbon/ammonium ratios and oxygen partial pressures with respect to the maximum hydroxybutyrate concentration.