Compound Mutation Breeding of <i>Streptococcus</i> e<i>qui</i> JC-63 for Producing High Molecular Weight Hyaluronic Acid and Optimization of Culture Conditions

Abstract

A strain of mutant Streptococcus equi JC-63, which can produce high molecular weight hyaluronic acid, was obtained from compound mutation breeding of Streptococcus equi JC-0 using 5-Bromouracil, UV rays and nitrosoguanidine as mutagenic agents. After inoculation for 25 generations, Streptococcus equi JC-63 showed inheritance stability, but not hemolysis. The culture conditions for producing HMW-HA were optimized in a 1-L shake flask through multi-factor orthogonal tests. Results showed the optimum ratio of fermentation medium comprised 50 g/L sucrose, 80 g/L corn steep liquor, 10 g/L glucose, 2 g/L MgSO4, 2 g/L NaHCO3, 2 g/L Na2HPO4, and 0.1 g/L UTP. Under these fermentation conditions, the molecular weight of the produced HA was 2.76 × 106 Da, and HA yield reached 4.12 g/L.