새우젓으로부터 혈전과 chitin 분해능을 지닌 균주 Bacillus licheniformis SC082의 분리 및 특성

Isolation and Characterization of Bacillus licheniformis SC082 Degrading Fibrin and Chitin from Shrimp Jeot-Gal

전통발효식품인 새우젓으로부터 혈전과 chitin 분해력이 우수한 균을 분리하였으며 16S rRNA 염기서열 분석으로 B. licheniformis와 가장 유사한 균주임을 확인하였다. 이 균주를 B. licheniformis SC082로 명명하였고, 최적 생육조건은 $37^{\circ}C$, pH 7.0, 염 농도 6%로 확인되었다. 이 균주의 기질특이성을 조사한 결과, 우수한 혈전분해력을 나타냈으며 1% 농도의 colloidal chitin의 첨가에 의하여 chitinase 활성이 증가됨을 관찰할 수 있었다. 또한 지질 분해능은 없었고 약한 skim milk 분해력을 가지고 있었다. SDS-PAGE와 zymogram 분석 결과, 이 균은 혈전분해효소 isozyme과 chitinase isozyme을 생성하는 균주로 확인되었다. 그 대략적인 분자량은 각각 22.0, 66.0, 72.0 kDa과 55.0, 62.0 kDa이었다. B. licheniformis SC082 균주가 생성하는 혈전분해효소는 pH 9.0 그리고 $50^{\circ}C$까지 안정하게 유지되었고, 이와 더불어, chitinase 활성은 pH 5, $45^{\circ}C$일 때 높게 나타났다. B. licheniformis SC082 균주의 DPPH 전자공여능법에 의한 항산화력은 농도의 증가에 따라 상승되었는데 $20\;{\mu}g$의 균상등액에 대한 항산화력은 약 31%으로 나타났다.

Shrimp Jeot-Gal is a popular traditional Korean fermented seafood and has been used for seasoning. We isolated a bacterium showing strong extra-cellular fibrinolysis and chitinase activity from shrimp Jeot-Gal and the strain was designated SC082. SC082 was identified as Bacillus licheniformis by 16S rRNA sequence homology search. B. licheniformis SC082 exhibited optimum temperature, pH, and salt concentration at $37^{\circ}C$, pH 7.0, and 6%, respectively. Substrate specificity of the culture supernatant from B. licheniformis SC082 was detected in fibrin, skim milk, and chitin plate. The fibrinolytic activity was highly maintained up to $50^{\circ}C$ at a pH of 7.0 for 3 hr and was stable up to pH 9.0 at $37^{\circ}C$ for 3 hr. The chitinase activity was remarkably induced by addition of 1.0% colloidal chitin and the pH and temperature optima of the enzyme were 5.0 and $45^{\circ}C$, respectively. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis and zymogram analysis, this strain produced three fibrinolytic isozymes and two chitinase isozymes. The approximate molecular weights of the putative fibrinolytic enzymes were 23.0, 62.0, and 72.0 kDa and those of the chitinases were 62.0 and 55.0 kDa, respectively. The antioxidant activity of SC082 was also measured by using 2,2-diphenyl-l-picryl-hydrazyl (DPPH) free radical. The DPPH radical scavenging was slightly increased in a dose-dependent manner.