Pageantagonistic Activity of Actinomycetes on Some Gram Negative and Gram Positive Bacteria

luteus showed that Six of them have inhibitory effects on both gram negative and gram positive pathogenic bacteria by using agar disk diffusion method. Of all six active Actinomycetes isolates, one of them named Streptomyces plicatus No. 24 was selected for further study on the basis of (a) broad spectrum activity and (b) larger inhibition zone against pathogen growth, in comparison with others. Minimum Inhibitory Concentration (MIC) of the crude culture filtrate of S. plicatus against Staphylococcus aureus was determined 1 as 0.004 mg ml. Gram positive pathogenic bacteria were more sensitive to its metabolites than gram negative ones. A commercial product containing S. plicatus or its effective metabolite(s) is suggested to avoid some of diseases in human and also bacterial resistance to conventional antibiotics. Key words: Actinomycetes Antagonistic activity Bacteria