The aim of this study was to isolate and identify marine bacterium with anti-methicillinresistant Staphylococcus aureus (MRSA) activity, and to purify the anti-MRSA compound, as well as to determine its activity and synergistic effects. Among the marine bacteria isolated in this study, the YJ-1 isolate had the strongest anti-MRSA activity. The YJ-1 isolate was identified on the basis of its biochemical characteristics and an analysis of 16S rRNA gene sequences. The YJ-1 isolate showed over 99.2% homology with Pseudomonas stutzeri, and was designated as a Pseudomonas sp. YJ-1. The optimal culture conditions were 25℃ and initial pH 7.0. For the purification of the anti-MRSA compounds, the YJ-1 was cultured in Pa PES-II medium, and the culture filtrates were extracted by ethyl acetate, hexane, and 80% MeOH. The 80% MeOH fraction was separated by a C18 ODS column, silica gel chromatography and a reverse phase HPLC, to yield three anti-MRSA agents, the MR1, MR2, and MR3 compounds. When the MR1 compound of 250 μg mL-1 concentration was applied to the MRSA cells, over 95% of bacterial cells was killed within 48 hr. Compared with vancomycin and ampicillin, the MR1 compound showed significant anti-MRSA activity. In addition, the anti-MRSA activity was increased by dose and time dependent manners. Furthermore, the combination of an MR1 compound with vancomycin produced a more rapid decrease in the MRSA cells than did the MR1 compound alone. Taken together, our results suggest that the Pseudomonas sp. YJ-1 and its anti-MRSA compounds could be employed as a natural antibacterial agent in MRSA infections.

서 론
 재료 및 방 법
  1. 해양미생물의 분리 및 표준 균주의 배양
  2. 분리 균주들의 항MRSA 활성 검정
  3. YJ-1 균주의 염기서열 분석 및 동정
  4. 조추출액의 열과 pH에 대한 안정성 검정
  5. YJ-1의 물질 분리, 정제와 항MRSA 활성 및 항균활성측정
  6. 시판 항생제와의 첨가 시간별 항MRSA 활성 비교측정
  7. MR1과 vancomycin의 병용 시 첨가 시간별 synergy효과 측정
 결과 및 고 찰
  1. 항MRSA 활성 균주 YJ-1의 분리 및 동정
  2. 조추출액의 열과 pH에 대한 안정성
  3. YJ-1 균주의 항MRSA 물질의 분리, 정제
  4. 최종 정제 순수물질의 항MRSA 활성 및 항균활성
  5. 시판 항생제와의 첨가 시간별 항MRSA 활성 비교
 적 요
 REFERENCES

• 우예주(대구가 톨릭대학교 의생명과학과, Department of Biomedical Science, Daegu Catholic University) | Ye-Ju Woo
• 정성윤(대구가 톨릭대학교 의생명과학과, Department of Biomedical Science, Daegu Catholic University) | Seong-Yun Jeong Corresponding author