Abstract:

One aliquot of the fermentation supernatant of Streptomyces parvus DY2741 using soybean powder as substrate was vacuum dried and the residue was extracted with water or 5 different organic solvent alone. The ethyl acetate extract was found to have good inhibitory activity against both S. aureus and E. coli. Another aliquot of the fermentation supernatant was directly extracted with ethyl acetate 3 times and the extracts were then pooled and condensed in a rotation evaporator and blown to dryness under nitrogen. Finally, the residue was dissolved in methanol and filtrated before purification/fractionization on Sephadex LH-20 column. As a result, two antibacterial fractions were obtained and the second eluting peak presented stronger inhibitory activities against both bacterial species. Thin layer chromatography was used to further fractionize the fraction with higher antibacterial activity. The subfaraction displaying a clear single spot was demonstrated by gas chromatography-mass spectrometry to contain a single composition, which was preliminarily identified to be dibutyl phthalate (DBP) based on searching Wiley Registry of Mass Spectral Data and infrared spectral analysis. Therefore, DBP is one of the major antibacterial substances produced by Streptomyces parvus DY2741.

Key words: marine Streptomyces parvus, antibacterial substance, solubility, separation and purification