P24: Strain improvement and statistical medium optimization for enhanced production of hyaluronic acid by Streptococcus zooepidemicus

Hyaluronic acid(HA) is a high molecular weight linear polysaccharide, used as a vitreous replacement, eye drop formula and a moisturizer in cosmetic formulations. In order to enhance HA productivity in bioreactor fermentations of Streptococcus zooepidemis, bioprocess optimizations such as strain improvement and medium optimization were carried out. High-yielding mutants screened through UV and NTG treatments showed remarkably higher HA productivity compared to the corresponding mother strains. Medium optimization was also carried out in order to find an optimal composition of the production medium. For this purpose, sequential statistical methods were adopted, such as one-factor-at-a-time method(OFAT), Plackett-Burman design, full or fractional factorial design(FFD), steepest ascent method(SAM) and response surface method(RSM). Approximately 3~4 fold increase in HA productivity was obtained in 5L bioreactor cultures performed under the optimized fermentation conditions with the high-yielding mutant strains.