Actinomycetes are Gram positive group of branching unicellular microorganisms, known for their ability to produce variety of antibiotics. The aim of the present study was to screen the genotoxic effect of actionmycetes isolated from soil samples collected from Amirthi National Park-river bank, Tamil Nadu, India. Out of ten actinomycetes isolates obtained the isolate named BT-7 was found to be active and the ethyl acetate (EA) extract obtained from the isolate was screened for genotoxic effect on human leucocyte culture. The effect of EA extract on human chromosomes was observed under microscope and noted for any aberrations. The active isolate showed significant genotoxicity on human chromosomes at higher concentration (100 µg) and the genotoxicity was compared with mitomycin, used as a positive control. Based on the results of this study it can be concluded that the secondary metabolites produced by actinomycetes species possess significant genotoxic effect on human chromosomes.

Keywords: soil actinomycetes, genotoxicity, mitomycin, human chromosomes, chromosomal aberrations.