Fermentation researches for antibiotic biosynthesis by Streptomyces 15.29 - Streptomyces microflavus

Abstract

Streptomyces 15.29 is an original Actinomycete strain that has been isolated from Vietnamese soil. Based on the ISP and 16s rDNA gene sequence determination  classification method we have basically determined that Streptomyces 15.29 is   Streptomyces  microflavus. Strain improvement by random selection and selection after UV light mutation is successful with strain’s  significantly better antibiotics  producing activity has been reached. The Streptomyces 15.29.21.23 is the our best mutant by now. Submerged fermentation on bioshaker machine and in 5 L, 500 L bioreactor has been carried out and the fermentation on bioshaker is the best, the fermentation in 5 L, 500 L bioreactor is equivalent, but its result is weaker than fermentation’s result on bioshaker. From the filtrate of fermentation broth  antibiotic were extracted best by ethyl acetate at pH 5,0. Thin layer chromatography  and column chromatography have showed that the antibiotic mixture has 4 components. Main  antibiotics component has been purified by column chromatography on silica gel, aluminum oxide, YMC and sephadex G10. The results of antibiotic assay showed that this component has strong antibiotic activity with the MIC values in the range from 0.11 to 0.30 µg/ml for S. aureus, P. mirabilis, S. flexneri, andS. typhi.