Spectrum of antibiotic resistance in cry4 positive local isolates of Bacillus thuringiensis

The sensitivity of thirteen different antibiotics was tested against cry4 positive isolates of bacillus thuringiensis (bt). au cry4 positive bt isolates and positive controls of cry4 gene ips78 and hd500 were found resistant to ampicillin,amoxicillin and bacitracin and were sensitive to chloramphenicol,erythromycin,kanamycin,neomycin,nalidixic acid,oxytetracyclin,polymixin,streptomycin,tetracyclin and vancomycin. to identify the plasmid borne antibiotic resistance gene,the competent cells of e. coli (dh5ά) were transformed with plasmid dna isolated from the bt cultures. the transformed e. coli showed resistance to ampicillin and amoxicillin. it was found that both ampicillin and amoxicillin were plasmid borne and present on 1.5kb and 1.0kb plasmids,respectively,while no antibiotic resistance genes were found on 23kb mega plasmid. copyright 2010 zoological society of pakistan.