Abstract:Streptococcus equin EF02 yielding 3.05 g/L HA was obtained through mutation and screening.After optimizing with single factor and orthogonal experiments,the fermentation medium was put into the 15 L fermentor.The yield of HA was 3.47 g/L,increasing by 13.77% compared with EF02 before optimization.It produced HA 3.66 g/L under the optimized fermentation conditions,increasing 20.00% comparing with EF02 before optimization.HA products were isolated and purified.The results showed that the extraction rate of HA,purity and the residual rate of protein was 98.36%,91.28%,0.97%,respectively.