Antibacterial activity of some actinomycetes isolated from soils of Alborz province, Iran

Screening of microorganisms for the production of novel antibiotics has been intensively pursued for many years by scientists. Actinomycetes have the capability to synthesize many different antibiotics. A total of 69 actinomycete isolates were recovered from soil samples collected from Alborz Province. Selected colonies (rough, chalky) of actinomycetes were purified. All screened isolates were identified morphologically and physiologically. And all of them belong to the Streptomyces genus. These were then assessed for their antibacterial activity against pathogenic bacteria. Four pathogenic test strains were used in this study including Staphylococcus aureus ATCC 6538, Bacillus subtilis ATTC 6633, Klebsiella pneumoniae ATTC 10031, and Escherichia coli ATCC 29998. Determination of antibacterial activities of isolated actinomycetes performed by using modified spektra-plak method and Mueller Hinton agar (Oxoid) plates. Antagonism was detected by formation of inhibition zone. Results of the study indicated that 12 isolates were active against S. aureus, 15 isolates against B. subtilis, six isolate against K. pneumonia, and four isolate were active against E. coli.