Isolation and screening for antimicrobial activities of culturable mesophilic streptomyces strains from north cyprus soils

A total of 249 different Streptomyces strains were isolated from different sites of the North Cyprus habitats for their antimicrobial potential. Out of these, 66 isolates exhibited inhibitory activity against at least one of the tested microorganisms. Approximately, 51% isolates produced antibacterial substances against Gram-positive bacteria, 6% against Gram-negative bacteria, and 23% against both Gramnegative and Gram-positive bacteria, whereas 18% of isolates showed antifungal activity. According to the spectrum of broadness, the two most active isolates were selected, and designed as KGG13 and KVK11. A great variety of morphological, physiological and biochemical features of selected strains were determined for their taxonomie position, and obtained data strongly suggested that these strains belong to the genus Streptomyces, confirmed by their antimicrobial activity in batch culture. In order to standardize the antibiotic production, some cultural conditions, such as the effect of different temperatures, nature of carbon sources, pH value, and time incubation in h, were determined. The highest antimicrobial activities were obtained when glucose and glycerol at 1% (w/v) was used as sole carbon source, at pHs 7.3 and 7.5 for the strains KGG13 and KVK11, respectively. © by PSP.