Isolation and screening of antibiotics producing streptomycetes from Western Region Soils of Saudi Arabia

الملخص EN

Streptomycetes group was studied in twenty-three soil samples of western region.

The highest density of this group was found in 3 soil samples collected from Al-Madinah Al-Munawwarah.

Six Streptomyces series were observed.

Gray series represented the most dominant isolates.

The highest antimicrobial activity was recorded in the case of gray and red series.

Streptomyces MR13 (red series) had a broad spectrum against test organisms.

Streptomyces MY18 (gray series) showed a high antimicrobial effect against Staph, aureus, Escherichia coli, P.

mirabilis and B.

subtilis.

Some antibiotics excreted by Streptomyces cultures had a very narrow spectrum against test organisms.

On the other hand, B.

subtilis was inhibited by 14 Streptomyces cultures followed, in descending order, by E.

Coli and Staph, aureus.

Candida albicans and Penicillium sp.

were only sensitive to only one Streptomyces isolate-