Antibacterial and antifungal activities of Actinobacteria isolated from Rathnagiri hills

Abstract

Article history: Received on: 18/08/2012 Revised on: 29/08/2012 Accepted on: 05/09/2012 Available online: 29/10/2012 This study was performed to isolate actinomycete colonies having antibacterial and antifungal activity from soil samples. A total of 27 actinomycete colonies were isolated in pure culture from five soil samples using Starch casein agar medium. Entire isolates were screened for their antimicrobial activity by agar plug method against five each of human pathogenic bacteria and fungi. Of this, 7 strains inhibits B. substilis, 3 strains inhibits Klebseilla sp, 6 strains inhibits B. cerus, 5 strains inhibits S. aureus and only 2 strains inhibits E. coli. Incase of fungi all the actinobateria has moderate activity with less fungal strains, only 1 strain (RA 5) inhibits entire fungus except Penicillium sp. The metabolites from potent strain was produced by fermentation, separated by centrifugation, it was tested for their antimicrobial activity against the test bacterial and fungal strains by well diffusion and disc diffusion method. In this study, the metabolites from RA5 (identified as Streptomyces sp.) have showed good antibacterial and antifungal activity. Since many isolates showed inhibitory activity against indicator bacteria, it is suggestive that Rathnagiri hill’s soil could be an interesting source to explore for antibacterial secondary metabolites.