• Journal of the Korean Applied Science and Technology
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• v.12 no.2
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• pp.121-130
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• 1995

This project has been worked out for isolation of EPA-producing bacteria from marine source of sea water, sea sediment and intestinal contents eviscerated from some red-muscle fish such as mackerel, horse-mackerel and spike fish. The samples were precultured on the media of PPES-II glucose broth and then pure-cultured on Nutrient agar and P-Y-M glucose. Lipids extracted from those bacterial mass collected by centrifugation were analysed in terms of lipid class and fatty acid composition. The results are resumed as follows : 1. 112 strains from sea water and 76 strains from sea sediment were tested for their EPA producing capability, but both strains of (SA-67 and SA-91) from the former and four strains(SS-35, 37, 51 and 71) from the latter have been proved to produce EPA above the level of 2% of total fatty acids. The strains such as GS-11, 29, 31, HM-9, 29, B-18, 33, 107, YL-129, 156, 203, 77, 104 and 256 which were isolated from fish intestinal contents, have also produced EPA at higher level than 2% of total fatty acids. 2. Contents of total lipids extracted from the cultures of these strains grown at $25^{\circ}C$, range from 2.8% to 6.9% (on dry weight %), and they are mainly composed of polar lipids($40.9{\sim}52.9%$) such as phosphatidyl glycerol($^{+}cardiolipin$)(?) and phosphatidyl ethanolamine ($33.8{\sim}40.0%$), with smaller amount of free fatty acid ($11.2{\sim}20.2%$). 3. EPA was isolated from a mixture of fatty acid methyl esters obtained from the lipid of each strain by HPLC in silver-ion mode and was identified by GC-Mass spectrometry. 4. The strains of SW-91, GS-11, GS-29, HM-9, B-18 and YL-203 grown at $25^{\circ}C$ have a level of 5% EPA in their total fatty acids, and the GS-11 and HM-9 strains show a tendency of increase in the EPA level with an increase of growth temperature.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.694-705
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• 2017

The aim of this study was to isolate and identify marine bacterium with anti-methicillin-resistant 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 $25^{\circ}C$ 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 $C_{18}$ 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 $250{\mu}g\;mL^{-1}$ 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.