Studies on interrelation between xylanase and glucose isomerase produced by streptomyces sp. K-53

Abstract

The present experiment was carried out to investigate relations between the induction process of xylanase by xylan and glucose isomerase production induced by xylose, a product of xylan hydrolysis. A microbial strain used was Streptomyces sp. K-53 which demonstrated the highest xylanase activity and considerably high glucose isomerase activity among stock culture strains isolated from soil. The results obtained are as follows : 1. Glucose isomerase, an intracellular enzyme, was induced by both xylan and xylose. On the other hand, xylanase which is an extracellular enzyme was induced only in the presence of xylan. 2. The maximum xylanase activity was obtained in a culture medium containing 4% xylan as a carbon source and 1% corn steep liquor as a nitrogen source. 3. Streptomyces sp. K-53 required K^(+) for the increased production of xylanase, whereas Mg^(++) and Co^(++), especially CoSO⁴ were required for the increased production of glucose isomerase. The optimum concentrations of KCl and CoSO⁴ were 3 x 10^(-3)M and 1 x 10^(-3)M, respectively. 4. The maximum activities of xylanase and glucose isomerase were observed after 4-5 days incubation at 30℃ in xylan medium, and the production of these two enzymes increased in parallel with cell growth.;토양에서 분리된 Streptomyces속 보존균주중에서 비교적 높은 glucose isomerase활성을 갖고 동시에 xylanase활성이 가장 높은 균주 Streptomyces sp₄K-53을 xylan을 함유한 영양배지에서 배양하여 xylan에의한 xylanase의 유도과정과 xylan의 분해산물인 xylose를 이용하여 glucose isomerase를 생성하는 과정의 일연의 관계를 알아보기 위해서 실험한 결과는 다음과 같다. 1. 균체내효소인 glucose isomerase는 xylan과 xylose에 의해 유도되었다. 반면, 균체외효소인 xylanase는 xylan 존재하에서만 유도되었다. 2. 탄소원으로 4% xylan과 진소원으로 1% corn steep liquor를 함유한 영양배지에서 xylanase의 효소활성이 가장 높았다. 3. 본 균주는 무기염으로 KCl이 xylanase에 요구되고 기타 이온은 저해제로 작용하지만, glucose isomerase는 Co와 Mg이온에 의하여 활성화되었다. KCl과 CosO₄의 최적농도는 각각 3×10^(-3)M, 1×10^(-3)M이었다. 4. Xylan을 기질로 한 배지에서 30℃에서 4-5일간 배양했을때 xylanase 및 glucose isomerase활성이 가장 높았으며, 이 두 효소의 생산성은 세포성장과 비례하여 증가하였다.