In silico optimization and low structured kinetic model of Poly[(R)-3-hydroxybutyrate] synthesis by Cupriavidus necator DSM 545 by fed-batch cultivation on glycerol

Glycerol was utilized by Cupriavidus necator DSM 545 for production of poly-3-hydroxybutyrate (PHB) in fed-batch fermentation. Maximal specific growth rates (0.12 and 0.3 h−1) and maximal specific non-growth PHB production rate (0.16 g g−1 h−1) were determined from two experiments (inocula from exponential and stationary phase). Saturation constants for nitrogen (0.107 and 0.016 g L−1), glycerol (0.05 g L−1), non-growth related PHB synthesis (0.011 g L−1) and nitrogen/PHB related inhibition constant (0.405 g L−1), were estimated. Five relations for specific growth rate were tested using mathematical models. In silico performed optimization procedures (varied glycerol/nitrogen ratio and feeding) has resulted in a PHB content of 70.9%, shorter cultivation time (23 h) and better PHB yield (0.347 g g−1). Initial concentration of biomass 16.8 g L−1 and glycerol concentration in broth between 3 and 5 g L−1 were decisive factors for increasing of productivity