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

In the present research, In vitro study of antagonistic properties of fifty soil actinomycetes against 10 bacteria which were: Salmonella typhi, Klebsiella pneumoniae, Serratia marsecense, E. coli, Proteus vulgaris, Streptococcus faecalis, Staphylococcus aureus, Bacillus subtilis, Bacillus cereus and Micrococcus 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 as 0.004 mg ml . Gram positive pathogenic bacteria were more sensitive to its metabolites than gram negative 1 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.