Abstract

This study was conducted with the aim of isolating and identifying entomopathogenic isolate of Bacillus thuringiensis (Bt) from the three different kinds of soils and to determine its antibiotic susceptibility. Soil samples were taken from three different uncultivated sites that have no history of treatment with Bt products. Isolation of the Bt strain was conducted based on the conventional biochemical method and the phenotypic characteristics of the isolated Bt were determined by making use of standard methods. 20 presumptively identified strains of Bt were subjected to antibiotic testing by using ampicillin, amoxicillin, tetracycline, streptomycin, and ofloxacin. Results show that the isolated strains of Bt were resistant to β-lactams (amoxicillin and ampicillin).

Keywords: antibiotic susceptibility, β-lactams, vermicast