포항 호미곶 해수에서 한천분해활성을 보이는 해양성 세균 SL-5을 분리하였으며 16S rDNA 염기서열분석으로 해양기원의 Thalassomonas 속과 가장 유사한 균주임을 확인하였다. SL-5 균주가 생성하는 한천분해효소(agarase)는 성장의존성인 것으로 확인되었고 효소활성을 위한 최적 pH는 pH 7.0(20 mM sodium phosphate 완충용액)이고 최적 온도는 $40^{circ}C$로 나타났다. 한천분해효소는 $80^{circ}C$까지 65%의 효소활성을 보이는 호열성 효소이지만, 내열성은 그리 높지 않았다. 한천 분해효소의 분해산물에 대한 TLC 분석결과, 본 효소가 $eta-agarase$라는 사실을 확인할 수 있었다. 분리한 Thalassomonas sp. SL-5 균주가 생산하는 한천분해효소를 이용하여 한천으로부터 다양한 기능성 한천올리고당을 생산하는데 있어 유용하게 사용될 것으로 기대된다.
A novel agar-degrading bacterium SL-5 was isolated from seashore of Homigot at Kyung-Buk province, and cultured in marine broth 2216 media. The bacterium SL-5 was identified as Thalassomonas genus by 16S rDNA sequencing with 96% identity. Growth rate was faster at $27^{circ}C$ than at $37^{circ}C$ and agarase was produced as growth-related. The optimum pH of the enzyme activity was 7.0 and the optimum temperature for the reaction was $40^{circ}C$. Although the enzyme had no thermostability, the enzyme activity was remained over 80% at $60^{circ}C$. The enzyme hydrolyzed neoagarohexaose to yield neoagarobiose as the main product, indicating that the enzyme is $eta-agarase$. Thus, the enzyme would be useful for the industrial production of neoagarobiose.
