Turkish Journal of Biology




Forty strains were isolated from six different soil samples. The soil samples were taken from the grasslands of Elmadağ, Çubuk, Gölbaşı, Haymana, Polatlı and Kazan near Ankara. As a result of the identification tests, 30 strains were identified as Bacillus subtilis, Bacillus megaterium, Bacillus firmus, Bacillus sphaericus, Bacillus thuringiensis, Bacillus pumilus and other Bacillus spp. The inhibitory effect of Bacillus strains against the test bacteria Escherichia coli, Staphylococcus aureus, Yersinia enterocolitica and Micrococcus flavus was examined. It was found that B. thuringiensis D1, B. thuringiensis D3 and B. megaterium Y6 strains showed an inhibitory effect on all of the test bacteria. To test the sensitivity of the new isolates, eight different antibiotics were used. The strains were tested for resistance to vancomycin, tetracycline, chloramphenicol, erythromycin, cephalothin, ampicillin sulbactam, gentamicin and penicillin G. The strains showed resistance to penicillin G (10 U), but all were sensitive to vancomycin. Isolates showed 97% sensitivity to chloramphenicol and 93% to tetracycline. Only B. subtilis K1 was observed to have penicillinase enzyme. The other strains were found to be penicillinase negative. While the proteolytic activities of the strains were observed in a range of 0.04-0.23 mg tirosin/ml, B. firmus G1, Bacillus spp. S1, Bacillus spp. S2 and Bacillus spp. S3 did not exhibit any activity. The profiles of plasmid DNAs of the strains were identified. Later, it was determined that five strains did not contain plasmid DNA while all other strains contained plasmid DNA from 1 to 4. The molecular weights of plasmid DNAs were found to range from 3.16 to 25.61 kb.


Bacillus spp., Soil, Antimicrobial activity, Antibiotic sensitivity, Proteolytic activity, Plasmid DNA

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