Dynamic modeling of internal and external metabolites with energetic and oxidative agents in hyaluronic acid production by <i>Streptococcus equi</i> subsp. <i>zooepidemicus</i>

This study presents an ordinary differential equation (ODE) based hybrid kinetic-metabolic model to predict the time evolution of biomass, glucose, hyaluronic acid (HA), and lactic acid during fermentation by <i>Streptococcus equi</i> subsp. <i>zooepidemicus</i>. The model incorporates simplified metabolic pathways and estimates the qualitative dynamics of internal, unmeasured metabolites involved in glycolysis, biomass synthesis, and HA production. Special emphasis is placed on the energetic molecules ATP/ADP, as well as the coenzymes NADH/NAD⁺, which are involved in redox reactions. These molecules have been shown to play regulatory roles in metabolism. The model predictions closely match the experimental data and provide insights into how varying glucose levels affect intracellular metabolic fluxes.