• The Korean Journal of Food And Nutrition
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• v.11 no.3
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• pp.347-353
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• 1998

An antibiotic for methicillin resistant Staphylococcus aureus(MRSA) produced by Streptomyces lydicus YSK-681 was extracted by chloroform, and then purified by the C18 reversed-phase HPLC and silica gel column HPLC. The molecular weight of the purified antibiotic was determined from the FAB analysis MS an m/z 1022.4 and 1036.4(M+H)+, indicating that the isolated antibiotic consisted of two similar compounds with the molecular weight difference of 14 m/z value. With the aid of the various nuclear magnetic resonance(NMR) spectroscopic techniques such as 1H NMR, 13C NMR, DEPT and HMQC spectroscopy, the characteristics of function al groups were deduced as the hydroxyl group and leucine. The MIC values of the purified antibiotic were observed at 1∼32 $\mu\textrm{g}$/$m\ell$ against Gram-positive bacteria compared to > 125 $\mu\textrm{g}$/$m\ell$ against Gram-negative bacteria or fungi. The antibiotic was active at 8 $\mu\textrm{g}$/$m\ell$ of MIC90 and S180 at the concentration of 500 $\mu\textrm{g}$/$m\ell$.

• Microbiology and Biotechnology Letters
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• v.21 no.1
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• pp.6-12
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• 1993

Among 294 Actinomycetes isolated from soil, a strain that had appeared to produce the highest level of chitinase selected for further studies. The selected strain was identified as a Streptomyces lydicus based on the data obtained from the morphological, biochemical and cultural experiments. The cultural conditions for the enzyme production were also examined, and the results obtained were as follows: the maximal enzyme production was attained when the cells were cultured at $30^{\circ}C$ for 6 days in the medium supplemented with 2% of colloidal chitin. The optimum initial pH of the medium was observed to be 8. It was also found that the most effective carbon and nitrogen sources were soluble starch and ammonium oxalate, respectively.

• Journal of Microbiology and Biotechnology
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• v.7 no.1
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• pp.56-61
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• 1997

A strain producing immunosuppressive substances was isolated from a soil in Cheju island. By morphological, cultural, and physiological studies, the strain was identified as Streptomyces lydicus MCY-524. Cultured broth was purified by silica gel, sephadex LH-20 and preparative HPLC and gave two immunosuppressive compounds, MCH-22 and MCH-32. They dramatically suppressed the B cell activation with lipopolysaccharide, T cell activation by mixed lymphocyte response, and primary T-dependent antibody response at a final concentration of 1 ${\mu}g$/ml. They also markedly suppressed the proliferation of lymphocytes induced by lipopolysaccharide, pokeweed mitogen, and concanavaline A at the same concentration. Their suppressive activities, which were comparable to those of cyclosporin A, suggested that they were potent and broad immunotoxic agents on the immune functions of murine lymphocytes.

• The Korean Journal of Food And Nutrition
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• v.11 no.3
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• pp.340-346
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• 1998

The strain YSK-681 has been selected for antibiotic-producing strain against methicillin resistant Staphylococcus aureus(MRSA) form 1,000 strains of actinomycetes which had been isolated from soil. The strain YSK-681 has been identified on the point of morphological, cultural, physiological and chemical characteristics. Forty-one taxonomic unit characters were tested and the data were analysed numerically using the TAXON program. The isolate was classified into the major cluster 29 of Streptomyces and best-matched to Streptomyces lydicus. Therefore, it was concluded that the isolate was identified to be Streptomyces lydicus.