• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.2
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• pp.165-173
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• 1996

Large amounts (300 grams) of natural red tide plankton, Cochlodinium polykrikoides, was collected at the Yokji island coastal waters, Kyeongnam, Korea, on October, 1993. Using the bioassay systems, bioactive materials were screened from methanol extracts of C. polykrikoides. Live C. polykrykoides was toxic to fishes, however, the water soluble and chloroform soluble fraction of their methanol extracts did not shown ichthyotoxicity (5 mg/ml), and toxicity to mice (50 mg, i.p,). These fractions did not show any peaks corresponding to paralytic shellfish toxins or diarryhetic shellfish toxins on the fluorometric HPIC chromatograms. Neither fractions did not show antibiotic activities by paper disk (10 mg/disc) test and chloroform soluble fraction showed only $20\%$ growth inhibition activity on the Lymphoid P-388 at the concentration of $180\;{\mu}g/ml$. Hemolytic activity was detected by both fractions. Fatty acid analysis by GC, GC/MS and proton NMR showed that the chloroform soluble fraction composed of $25.3\%$ of DHA (dorosahexaenoic acid) and $15.3\%$ of IPA (eicosapentaenoic acid) as the hemolytic components.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.3
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• pp.319-328
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• 1997

To develop a beneficial microbial feed for the cultivation of rotifer, Brachionus plicatilis, an aerobic photosynthetic bacterium, Erythrobacter sp. $S\;\pi-I$ was isolated from marine structure at Haeundae beach in Pusan, Korea. Feeding effects of Erythrobacter sp. $S\;\pi-I$ on the growth of rotifer were analyzed comparing to other feeds such as PSB (purple nonsulfur bacteria), Chlorella sp. and baker's yeast. Erythrobacter sp. $S\;\pi-I$ contained more linoleic acid $(C_{18:3\omega3})$ and oleic acid $(C_{18:1\omega9})$ and amino acids than PSB (purple nonsulfur bacteria), Chlorella sp. and baker's yeast. The rotifer fed on Erythrobacter sp. $S\;\pi-I$ showed better effects than those fed on other feeds in the individual growth, size and weight. Also, the rotifer especially contained more eicosapentaenoic acid $(C_{20:5\omega3})$ and docosahexaenoic acid $(C_{22:6\omega3})$ in case of Erythrobacter sp. $S\;\pi-I$ feeding than the other feeds. In case of the feed of PSB and baker's yeast docosahexaenoic acid $(C_{22:6\omega3})$ did not show. In amino acid analysis, the rotifer fed on Erthrobacter sp, $S\;\pi-I$ showed more amino acid content comparing to those fed on other diets. Especially, arginine, isoleucine, histidine, lysine, methionine, phenylalanine, threonine, which are essential amino acid for fish growth, showed high contents. These results suggested that the aerobic photosynthetic bacterium, Erythrobacter sp. $S\;\pi-I$ would be a beneficial microbial teed for the cultivation of rotifer.