Isolation and characterization of antibiotic-producing <i>streptomyces SPP</i>

Abstract

Seven species of Streptomyces were isolated from soil samples in various locations at the University of Nigeria, Nsukka and characterized with the view of determining their antibacterial efficacy. The samples were pre-treated with calcium carbonate before seeding onto Actinomycetes isolation media; arginine-glycerol salts medium and M-medium supplemented with 1% sterile soil extract (to mimic the natural environment). Based on the cultural, morphological, microscopic, biochemical and physiological characteristics, the following organisms were identified: Streptomyces xanthocidicus, Streptomyces albosporeus, Streptomyces albolongus, Streptomyces catenulae, Streptomyces galtieri, Streptomyces aburaviensis and Streptomyces nigrifaciens.Three of the isolates were observed to have significant antibiotic producting potential, and the antibacterial activity of the produced antibiotics (cultural supernatants of the isolates grown on Czapek’s dox yeast extract broth) was assessed using the well-in-agar diffusion method. The antibiotic produced by Streptomyces aburaviensis had broad-spectrum inhibitory activity on Gram positive cocci (Staphylococcus aureus), Gram positive rod (Bacillus subtilis) and Gram negative rod (Klebsiella aerogenes), antibiotics produced by while Streptomyces albosporeus and Streptomyces catenulae had narrow spectrum inhibitory activity on Gram negative rod (Salmonella spp).