Kinetics of hyaluronic acid production by Streptococcus zooepidemicus considering the effect of glucose

Abstract

An unstructured model of hyaluronic acid (HA) fermentation by Streptococcus zooepidemicus considering the effect of glucose was proposed and validated. Experiments were performed in a glucose concentration range of 10–60 g l −1 in a 2 l bioreactor of batch mode. Three different models, namely, the Logistic equations for cell growth, the Logistic incorporated Leudeking–Piret-like equation for glucose consumption, and the Logistic incorporated Leudeking–Piret equation with time delay, Δ t, for HA productions were proposed. The kinetic parameters were estimated by fitting the experimental data to the models. Simulation was made using the estimated kinetics parameter values and was compared with the experimental data. For glucose inhibition, S. zooepidemicus tolerated up to 40 g l −1 glucose. Beyond this concentration, cell growth was inhibited. The Han and Levenspiel model and the Teissier-type model gave the best fit for all the systems studied with R 2 of 0.997 and 0.985, respectively.