Marine medaka (Oryzias dancena)를 이용하여 다양한 수계 염분환경에 따른 주요 수산 병원체들의 감수성과 병원체와 어체 간 생리적 상호작용을 분석하였다. 세균성 병원체인 Edwardsiella piscicida, Vibrio anguillarum 및 V. harveyi의 염분별 생장분석을 분석하였다. 염분별 균주의 생장분석 결과 E. piscicida는 0 psu에서 7±0.2 mm 로 가장 높은 생장을 나타냈으며, V. anguillarum 및 V. harveyi는 30 psu에서 각각 10.8±0.763 및 14±1.732 mm로 활발한 생장을 나타내었다. 3종의 세균성 병원체 중 Marine medaka에 감수성이 가지는 E. piscicida 균주를 사용하여 염분별 액상배지에서 배양한 뒤, 인위감염시켜 염분별 환경에서 누적폐사율을 분석한 결과, high level 1 (3.85×1011 CFU/ml)에서 10 psu 조건에서 60%의 가장 높은 생존율이 나타냈으며, high level 2 (7.7×1010 CFU/ml)에서는 20 psu에서 25%의 가장 낮은 생존율을 보였다. 또한 E. piscicida 균주의 ECP protease 활성 분석 결과, 20 psu에서 가장 높은 효소 활성을 보였다. 본 연구 결과는 염분 환경에 따른 병원체의 생리적 특성과 감염력, 및 숙주의 감수성에 중요한 영향을 미치며, 해양 환경 변화에 따른 수산 질병 예측 및 예방 전략 수립에 유용한 기초 자료로 활용될 수 있다.

Marine medaka (Oryzias dancena) was used to analyze susceptibility to major aquatic pathogens and to investigate the interactions between pathogens and hosts under varying salinity conditions. The bacterial pathogens Edwardsiella piscicida, Vibrio anguillarum, and V. harveyi were evaluated for growth across different salinity levels. Growth analysis revealed that E. piscicida exhibited the greatest growth (7 ± 0.2 mm) at 0 psu salinity, while V. anguillarum and V. harveyi showed vigorous growth at 30 psu salinity, with lengths of 10.8 ± 0.763 mm and 14 ± 1.732 mm, respectively. Among the three bacterial pathogens, a challenge experiment was conducted using E. piscicida, to which marine medaka is susceptible. The pathogen was cultured in broth media under various salinity conditions, and marine medaka acclimated to different salinities were challenged by immersion at five bacterial concentration levels. Cumulative mortality was then monitored under each salinity condition. Under the high concentration level 1 condition (3.85×1011 CFU/ml) of E. piscicida, the highest survival rate (60%) of marine medaka was observed at 10 psu salinity, whereas under the high concentration level 2 condition (7.7×1010 CFU/ml), the lowest survival rate (25%) was observed at 20 psu salinity. In addition, analysis of the extracellular protein (ECP) protease activity of E. piscicida at different salinities showed the highest enzymatic activity at 20 psu salinity. These results show that changes in salinity have a significant effect on the physiological characteristics of the pathogen and the susceptibility of the host, thereby influencing mortality rates. This study can be used as basic for predicting the occurrence and establishing preventive strategies against aquatic diseases under changing salinity environmental conditions.

서 론
재료 및 방법
    1. 균종 및 균주
    2. 염분별 세균성 병원체의 생장 분석
    3. 실험어
    4. 염분별 E. piscicida 감염에 대한 영향
    5. 염분별 E. piscicida ECP protease 활성
    6. 통계처리
결 과
    1. 균주의 염분별 생장 분석
    2. 염분별 E. piscicida에 대한 marinmedaka의 감수성 분석
    3. 염분별 E. piscicida ECP protease 활성
고 찰
사 사
참고문헌

• 강예재(국립군산대학교 수산생명의학과) | Yue Jai Kang (Department of Aquatic Life Medicine Kunsan National University, Gunsan 54150, Korea) Corresponding author
• 최희재(국립군산대학교 수산생명의학과) | Hee-Jae Choi (Department of Aquatic Life Medicine Kunsan National University, Gunsan 54150, Korea)
• 이현학(국립군산대학교 수산생명의학과) | Hyunhak Lee (Department of Aquatic Life Medicine Kunsan National University, Gunsan 54150, Korea)
• 정세진(국립군산대학교 수산생명의학과) | Sejin Jeong (Department of Aquatic Life Medicine Kunsan National University, Gunsan 54150, Korea)
• 서정우(국립군산대학교 수산생명의학과) | Jungwoo Seo (Department of Aquatic Life Medicine Kunsan National University, Gunsan 54150, Korea)
• 조성현(국립군산대학교 수산생명의학과) | Seonghyun Jo (Department of Aquatic Life Medicine Kunsan National University, Gunsan 54150, Korea)
• 소준현(국립군산대학교 수산생명의학과) | Junhyun So (Department of Aquatic Life Medicine Kunsan National University, Gunsan 54150, Korea)
• 김원혁(국립군산대학교 수산생명의학과) | Wonhyuk Kim (Department of Aquatic Life Medicine Kunsan National University, Gunsan 54150, Korea)