Optimization of an Extracellular Dextranase Production from Lipomyces starkeyi KCTC 17343 and Analysis of Its Dextran Hydrolysates

We optimized dextranase culture conditions by batch fermentation using Lipomyces starkeyi KCTC 17343. Furthermore, dextranase was purified by an ultra-membrane, and then dextran hydrolyzates were characterized. Cell growth and dextranase production varied depending on the initial culture pH and temperature. The conditions of optimal dextranase production were met in a pH range of 4-5 and temperature between 25-30℃. At optimal fermentation conditions, total enzyme activity and specific enzyme activity were about 4.85 IU/㎖ and 0.79 IU/g cells, respectively. The specific growth rate was examined to be 0.076 hr-¹. The production of dextranase in culture broth was very stably maintained after mid-log phase of growth. The enzyme hydrolyzed dextran into DP (degree of polymerization) 2 to 8 oligodextran series. Analysis of the composition of hydrolysates suggested that the enzyme produced is an endo-dextranase.