Isolation and Charaterization of Myxobacteria with Proteolytic Activity

Seven isolates showing strong proteolytic activity, KYC 1028, 1100, 1134, 1139, 1151, 1159, and 1182, were collected. Out of them, the broth of KYC 1134 and KYC 1139 showed the high proteolytic activity measured by azocazein. To determine 16S rDNA sequences for identification, 16S rDNA of seven isolates were amplified and compared with the 16S rDNA sequences of other myxobacteria at NCBI. It is evident from the phylo-genetic tree that the isolates belong to the genus Myxococcus. Sharing high percentage similarity values with myxobacteria, the 16S rDNA sequences were involved in two species, Myxococcus macrospores and M. Fulvus. Biochemical characteristics of KYC 1134 broth, which showed the highest proteolytic activity, showed increased activity 8 times to seven days after culture, and protein production were increased gradually and stopped at five days. The broth had optimal temperature at $60^{\circ}C$ for proteolytic activity, and stability of pH was ranged from pH 5 to 10, at $50^{\circ}C$ and 60, respectively. To classify proteases being in the broth, ten inhibitors were determined and only bestatin showed 27% inhibition effect. The inhibition result demonstrates that the broth contains kinds of amino peptidases and other exopeptidases.

Myxobacteria의 Proteolytic Activity 특성

Proteolytic 활성을 나타내는 균주 KYC 1028, 1100, 1134, 1139, 1151, 1159, 1182등 7개 균주를 선발하였고, 이중 KYC 1134와 KYC 1139이 azocazein을 이용한 proteolytic 활성 조사에서 높은 활성을 나타내었다. 선발된 7개 균주의 동정은 16S rDNA 염기서열를 조사하였으며, NCBI에서 myxobacteria의 16S rDNA와 비교분석 하여 Myxococcus속 M. macrospores와 M. Fulvus에 높은 상동성을 나타내었다. 활성이 가장 높은 KYC 1134배양액의 생화학적 특성은 배양 7일까지 활성이 10배 증가하고, 단백질 생산도 함께 증가하였다. 배양액의 적정 proteolytic활성 온도는$60^{\circ}C$이고, pH 5에서 10까지 활성이 안정적이었다. 배양액의 proteases의 종류를 확인하기 위하여 11개의 inhibitors를 조사하여 bestatin만이 억제효과를 나타내어 amino peptidases와 exopeptidases와 종류가 배양액에 존재하는 것으로 보인다.