Factors Affecting the Biological Activity of Streptomyces aureofaciens MY18 and Str. roseviolaceus MR13

The biological activity of Streptomyces aureofaciens MY18 and Streptomyces roseviolaceus MR13 (local isolates) as influenced by temperature,aeration, different media and carbon and nitrogen sources were investigated. It was found that biomass., growth parameters and antibiotic activity of bOth strains were highly affected by these factors. The first strain showed higher temperature range than that observed for second strain. The optimum temperature for growth and antibiotic production of both strains was 30°C. Shaken cultures supported growth and antibiotic activity than st(\tic cultures. Starch and nitrate stimulated antibiotic production in the culture filtrate of bOth organisms. The optical density of golden yellow soluble pigment of Strepiomyces MY18 (gray series) cultures increased with the increase of antibiotic activity, which can be used as an indication for antibiotic concentration and its activity. Introduction Production of antibiotics by micro-organisms is highly affected by many factors. Prescott and Dunn!l) stated that the propagation medium contains, in addition to the usual sources of carbon, nitrogen, minerals and buffers, precursors, (these are known to be of value for increasing the total or the yield ofa given type of antibiotic). SaUe!2] mei1tion~d that all antibiotic producing organisms which have been studied must have free oxygen for normal metabolic activity. With respect to the effect-of different carbon sources, Orlova and Andrianova!3] mentioned that Actinomyces rimosus LST grows well in media containing starch, ~altost]:, glucose, galactose, or ribose and poorly in a medium containing arabinose, whereas sucrose, .lactos~, xylose and rhamnose are not utilized. They also added that