Optimizing hyaluronic acid production by Streptococcus zooepidemicus using taguchi method: effects of temperature and pH.

Abstract

The cost-effective and high-yield production of hyaluronic acid (HA) by microbial means remains challenging, necessitating the optimization of existing processes through the implementation of novel approaches. The present study investigates the production of HA under varying temperature and pH conditions utilizing independent, fully controlled fermenters. The synthesis of HA was evaluated at four temperatures (32 °C, 35 °C, 37 °C, 40 °C) and four pH levels (6.5, 7.0, 7.5, and 8.0), with optimal parameters identified through the Taguchi design methodology. The Taguchi optimization method effectively identified 37 °C and pH 6.5 as the optimal conditions for HA production corresponding to the highest signal-to-noise (S/N) ratios of 58.18 and 57.55, respectively. These conditions resulted in a maximum yield of 1.08 g.L^-1, demonstrating the efficacy of this parameter combination in maximizing production efficiency. The carbazole method was utilized to quantify the production of HA following a five-hour fermentation period, with the culture conditions subjected to a statistical comparison. A temperature of 37 °C yielded significantly higher HA levels than 32 °C and 40 °C (Dunn test, respectively p = 0.019, p = 0.001). The lowest HA production was observed at 40 °C, while the 32 °C group exhibited relatively low variation in HA production. Furthermore, the hourly bacterial counts demonstrated a direct correlation between bacterial proliferation and HA synthesis, with the highest bacterial growth observed at 37 °C and pH 7.0. This study highlights the trends in HA concentration under different temperature and pH conditions during the pre-fermentation phase, offering critical insights for optimizing HA production.