Enhanced hyaluronic acid production by a two-stage culture strategy based on the modeling of batch and fed-batch cultivation of Streptococcus zooepidemicus

This study aimed to enhance hyaluronic acid (HA) production by a two-stage culture strategy based on the modeling of batch and fed-batch culture of Streptococcus zooepidemicus. Batch culture had higher specific HA synthesis rate while fed-batch culture had higher specific cell growth rate. The lower specific HA synthesis rate in fed-batch culture resulted from the competition of cell growth for the common precursors at a low substrate concentration. Based on the modeling of batch and fed-batch culture of S. zooepidemicus, a two-stage culture strategy was proposed to enhance HA production. S. zooepidemicus were cultured in a fed-batch mode with sucrose concentration maintained at 1.0 ± 0.2 g/L during 0–8 h and then batch culture was performed during 8–20 h with an initial sucrose concentration of 15 g/L. With the proposed two-stage culture strategy, HA production was increased to 6.6 g/L compared with 5.0 g/L in batch culture with the same total sucrose. The enhanced HA production by the proposed two-stage culture strategy resulted from the decreased inhibition of cell growth and the increased transformation rate of sucrose to HA.