SELECTION OF A STREPTOCOCCUS-EQUI MUTANT AND OPTIMIZATION OF CULTURE CONDITIONS FOR THE PRODUCTION OF HIGH-MOLECULAR-WEIGHT HYALURONIC-ACID

A high molecular weight hyaluronic acid-producing mutant, designated a s Streptococcus equi KFCC 10830, was derived from Streptococcus equi A TCC 6580 by the serial selection programs after NTG treatment. The sel ected mutant had nonhemolytic, hyaluronidase-negative, kanamycin-resis tant, and highly viscous characteristics. Various culture conditions w ere optimized in a 5-l fermentor for the production of high molecular weight hyaluronic acid. When lysozyme was added to the culture broth d uring cultivation, the molecular weight of hyaluronic acid increased f rom 2.9 x 10(6) to 3.8 x 10(6). The optimum temperature and pH were 37 degrees C and 7.0, respectively. The molecular weight of hyaluronic a cid at these conditions was 3.8 x 10(6). The effect of impeller type o n the molecular weight of hyaluronic acid was also examined. When the intermig-type impeller was applied to the fermentor, the molecular wei ght of hyaluronic acid was 4.8 x 10(6). The molecular weight of hyalur onic acid increased as high as 5.0 x 10(6) when the agitation speed wa s increased up to 1.299 rpm. The highest molecular weight of hyaluroni c acid, 4.8 x 10(6), was achieved at an aeration rate of 1.0 vvm. In a ddition, pilot-scale production of hyaluronic acid was successfully pe rformed in a 100-l fermentor. Hyaluronic acid with a molecular weight of 3.2 x 10(6) was accumulated at a concentration of 6-7 g l(-1) in th e culture broth. Accordingly, culture conditions, such as the addition of lysozyme, temperature, pH, impeller type, agitation speed, and aer ation rate, were found to be major factors affecting the molecular wei ght of hyaluronic acid as well as its production.