Based on the analysis of metabolic pathway Streptococcous zooepidemicus for hyaluronic acid (HA) synthesis,nucleotide,especially uracil,was considered to be important to cell growth and metabolism.When 0.005 g·L -1 uracil added in the media in which yeast extract as complex nitrogen source,cell growth and HA production were increased by 32% and 34% respectively.From analysis of amino acid in fermentation process,it was show that arginine(Arg)was needed for cell metabolism,and concentration of free Arg maintained at 0 g·L -1 in fermentation process,which was proposed to limit cell growth and HA production.By shake flask experiment HA concentration reached 0.510 g·L -1 whene 0.06 g·L -1 Arg added,in the fermentation with 2.5 L fermentor,when uracil 0.005 g·L -1 and Arg 0.06 g·L -1 were added,the rate of cell growth increased,maximum of specific growth rate,concentration of HA and HA molecular weight reached 0.67 h -1 ,5.2 g·L -1 and 2.15×10 6 Da from 0.54 h -1 ,4.2 g·L -1 ,2.0×10 6 Da,respectively.
