Characterization and Xylanase Productivity of Streptomyces sp. YB914

A strain YB914 was isolated from soil as a producer of the extracellular xylanase, which catalyzes the hydrolysis of oat spelt xylan. The strain YB914 was identified as Streptomyces sp. on the basis of its morphological, cultural and biochemical properties. The xylanase of culture filtrate was the most active at $55^{\circ}C$ and pH 5.5, and retained 80% of its maximum activity at the range of pH 4.5~7.0. In order to optimize the culture medium for xylanase production, ingredients of G.S.S medium were replaced by several carbohydrates. The carbohydrates such as oat spelt xylan, corn cob xylan, wheat bran and lactose increased the xylanase productivity of Streptomyces sp. YB914. However, xylanase production was greatly repressed by galactose or arabinose. The maximum xylanase productivity was reached to 48 U/mL in the modified medium containing 1% oat spelt xylan and 1.5% lactose.

Xylanase를 생산하는 Streptomyces sp. YB914의 특성과 효소 생산성

토양으로부터 세포외로 xylanase를 분비 생산하는 방선균 YB-914가 분리되었으며, 형태, 배양, 생화학적 특성을 조사한 결과 Streptomyces 속 균주로 확인되었다. 분리균의 배양상등액에 존재하는 xylanase는 pH 5.5과 $55^{\circ}C$의 반응조건에서 반응성이 가장 높았으며, pH 4.5~7.0 범위에서 최대활성의 80% 이상을 나타냈다. Xylanase의 생산을 위한 배지를 최적화하기 위해서 G.S.S 배지성분을 여러 종류의 탄수화물로 대체하였다. Oat spelt xylan, corn cob xylan, 밀기울 및 유당과 같은 탄수화물은 Streptomyces sp. YB914의 xylanase 생산성을 증가시키는 것으로 확인되었으며, galactose와 arabinose는 효소 생산을 크게 억제하였다. Oat spelt xylan(1%)와 유당(1.5%)을 함유한 변형배지에서 xylanase의 최대생산성이 48 U/mL로 확인되었다.