Streptococcus zooepidemicus ATCC 35246, an organism acquired from American Type Culture Collection was capable of producing hyaluronic acid at 180.23 mg/ml. Upon exposing to UV-light for 80-120 seconds for 3 rounds, a mutant designated CU 47 capable of producing hyaluronic acid at 370.13 mg/l was obtained. Further mutation via NTG (N-methyl-N'-nitro-N-nitrosoguanidine) at 50 micrograms/ml, 5-40 minutes, 37 ํC yielded a number of mutants producing hyaluronic acid in higher yield. Subsequent isolation and mutation via NTG for 4 additional rounds, a mutant namely CUN5-10 was obtained with ability of producing hyaluronic acid at 585.85 mg/l Optimal conditions for hyaluronic acid production by CUN5-10 were : cultivation at room temperature (28-32 ํC), initial pH of 7.5, initial concentration of sucrose at 10 g/l with agitation rate of 200 rpm. Under such conditions CUN 5-10 could produce hyaluronic acid at 829.11 mg/l. The addition of lysozyme at 40,000 units to the culture medium could raise hyaluronic acid yield up to 2.50 g/l while the addition of tween-80 at 0-2% (v/v) did not show any significantly increase in hyaluronic acid production.
