Isolation and identification of actinomycetes isolated from karachi soil and screening of antimicrobial compounds

Twenty strains of actinomycetes were isolated from a soil sample in Karachi and screened for antimicrobial activity both by primary screening method (perpendicular streak and spot inoculation method) and secondary screening method (agar well diffusion method) against several test organisms including bacteria and fungi. Out of twenty strains eight showed broad spectrum activity in primary screening. The secondary screening was done with those strains which gave activity against test microorganisms in primary screening. The strains were identified using various biochemical tests and their optimum growth conditions (temperature, pH and at different concentrations of NaCl) were also determined. The most promising strain amongst all was SZ020 which was identified as Pseudonocardia sp.