Abstract:The molecular weight of hyaluronic acid significantly affected its physicochemical properties and application effects. Effects of different culture conditions on the molecular weight of hyaluronic acid synthesized by Streptococcus equisimilis was compared,the results of which indicated that glucose with high concentration benefited the synthesis of long-chain hyaluronic acid. The concentration of glucose had significantly effect on the molecular weight of hyaluronic acid. With the initial concentration of glucose enhancing from 20 g/L to 80 g/L,the molecular weight of hyaluronic acid was increased to 2.02×106 from 1.24×106,i.e.,increased by 62.9%. Feeding mode of glucose significantly affected the molecular weight of hyaluronic acid. The molecular weight of hyaluronic acid was respectively 1.53×106 and 1.42×106 through interval and continuous feeding modes of glucose,which was decreased by 19.9% and 25.7% by comparing with batch culture. Low temperature was beneficial to the synthesis of high-molecular-weight hyaluronic acid. Under the culture condition of 33 ℃,the molecular weight of hyaluronic acid could reach to 2.54×106 at the maximum. pH also significantly affected the molecular weight of hyaluronic acid. When pH was 8,the molecular weight of hyaluronic acid reached to the highest 2.38×106. Dissolved oxygen with higher level benefited the sythesis of high-molecular weight hyaluronic acid,within the concentration range of 0~45% of dissolved oxygen,the molecular weight was increased to 2.43×106 from 1.16×106 with the increasing concentration of dissovled oxygen,increased by 109.4%.
