Abstracto

Antibacterial activity of some isolates of actinomycetes fromYemeni soils

Amina El-Shaibany, Gamal El-Didamony

Actinomycetes are one of the most attractive sources of antibiotics and other biologically active substances of high commercial value. It accounts roughly for two-thirds of the total known antibiotics. This study was undertaken to characterize antibacterial activity of some actinomycete isolates occurring inYemeni soils. Fourteen soil sampleswere collected from cultivated soil in sixGovernorates ofYemen. Sixty three actinomycete isolates were obtained by using the dilution plate technique method. Using diffusion methods twenty isolates gave antibacterial activities. Two isolates namely YI(l)d and YI(8)g gave the highest antibacterial activities against the tested bacterial strains. The bioutography revealed that the antibacterial activity against tested organisms was due to the presence of antibiotic. Ethyl acetate and acetone were found to be the best solvents to extract the antibiotic substance(s) fromactinomycete isolates numberYI(l)d and YI(8)g respectively. The extracts were concentrated by evaporation under vacuum and the residues were tested for activity. Further purification was done by using preparative thin layer chromatography that gave more than one spot i.e. there was more than one antibiotic produced by isolate numberYl(l)d.