Studies On The Enhanced Production Of Hyaluronic Acid By Streptoccous Zooepidemicus H24

Hyaluronic acid (HA) is a high-molecular-weight linear polysaccharide.HA has the unique water-binding and retention capacity. It is widely used in cosmetics, medicines for wound dressing, eye drops, and medicines for ophthalmic surgery and arthritis.Streptococcus zooepidemicus H24, a strain with high-HA productivity, was used in this study. Oxidative stress in Streptococcus zooepidemicus H24 was investigated. And effect of different types of surfactants on cell growth and hyaluronic acid (HA) production by Streptococcus zooepidemicus H24 was studied. The nutritional conditions and addition concentration of glucose during HA fermentation in 2.5 L fermenter were determined. Following the main results were summarized:Oxidative stress in Streptococcus zooepidemicus H24 was investigated. The results showed that a 21 % increase in HA yield resulted from NaClO treatment(0.05μL/mL) before inoculation because of the spontaneous mutagenesis in Streptococcus zooepidemicus H24. A 20 % increase in HA yield was obtained due to adding H2O2 (0.1 mmol/L) at 4 h in the course of HA fermentation which stimulated HA capsule production.Effect of different types of surfactants on cell growth and hyaluronic acid (HA) production by Streptococcus zooepidemicus H24 was investigated. Furthermore, effect of cationic surfactant CTAB on the growth and HA production was also investigated in a 2.5 L fermentor. The concentration of HA increased from 5.1 g/L to 5.7 g/L by adding CTAB during 8 h and 12 h. Those results indicated that CTAB enhanced HA production, and CTAB addition benefited the capsule remove of Streptococcus zooepidemicus during fermentation.Effect of yeast extract concentration and glucose addition concentration on HA yield and molecular weight in 2.5 L fermentor was investigated. When the initial yeast extract concentration was 20 g/L ,HA yield and molecular weight could reach 4.7 g/L and 2.00×10~6 Da. When adding 30 g/L glucose at 10 h during HA fermentation, HA yield and molecular weight could reach 5.3 g/L and 2.14×10~6 Da.In 2.5 L fermentor, adding 0.005 g/L urail in fermentation culture made the velocity of HA production improve. Then HA yield and molecular weight could reach 5.5 g/L and 2.20×10~6 Da. When adding 0.005 g/L urail and adding 30 g/L glucose at 10 h during HA fermentation at one time, HA yield and molecular weight could reach 5.8 g/L and 2.34×106 Da, respectively.