Antimicrobial activity and molecular identification of Streptomyces strains isolated from Saudi Arabia.

Actinomycetes are group of Gram-positive bacteria with high GC-content in their DNA. They are extremely useful for the pharmaceutical industry due to their seemingly unlimited capacity to produce secondary metabolites with diverse biological activities and chemical structure. The genus Streptomyces constitutes 50% of the total population of soil actinomycetes and about 75% of commercially and medicinally useful antibiotics that have been derived from this genus. The present study aimed in isolation of bioactive compound showing antimicrobial activities from soil Streptomyces, previously isolated and morphologically characterized from Jazan in Saudi Arabia. Six potent Streptomyces strains: JS3, JS4, JS6, JD7, JA8 and JA10 were chosen for antimicrobial activity screening against 5 human pathogenic bacteria and 5 phytopathogenic fungi before molecular identification was done. For antibacterial activity, the results showed that inhibition zones were found to range between 3.25-26.875 mm diameters, while for antifungal activity, it ranged between 13.3-40 mm diameters. The entire sequence of the 16S rDNA was determined for the strains JS6, JD7, JA8 and JA10 and deposited in the GenBank. Future studies of actinomycetes isolated from the Kingdom of Saudi Arabia's soils will assist in the discovery of new compounds that would be of industrial, pharmaceutical and agricultural importance.