General Evaluation of Biocide (Bt-ASF-1) Produced from Iraqi Isolate of Bacillus thuringiensis
Ali S. Ahmed , S. Kadim , Firas. M. Sajet , jazair A. Juwaed , A. Hamdy, I. Atyia , S. A. Alhamid
Abstract

General evaluation of isolate Bacillus thuringiensis (Bt-ASF-1) used as biocide in meddle scale application was conducted. Some morphological and confirmation tests were achieved. The sensitivity tests had been accomplished by diffusion and dilution techniques to determine the response of isolate against the antibiotics. The results of diffusion tests showed to the sensitivity of bacteria to antibiotics of cefixime, erythromycin, gentamicin and tetracycline respectively. It was resistant to trimethoprim sulfonamide (TMP), bacitracin, penicillin and all its generations, and moderate resistance to nalidixic acid. Minimum Inhibitory Concentration (MIC) for amoxicillin was ranged between 30-40 µg/mL and these results are an approximation of the universal findings. Curing experiments showed the effective role of sodium dodecyl sulfate (SDS) (1.5%) comparing with temperature. The bacterial cells became sensitive to amoxicillin and TMP. The curing by temperature did not differ significantly from control treatment in plasmid pattern or antibiotics response. Plasmid profile referring that curing by SDS has been caused disturbance in beta -lactamase genes through the sensitivity to amoxicillin and remaining resistance to ampicillin. Curing isolate by SDS also became more sensitive to nalidixic acid, erythromycin and tetracycline respectively. It was found from the curing treatments the complexity distribution of r-genes between different plasmid size and chromosome but not effect on their insecticidal ability.
Key words: Bacillus thuringiensis (Bt-ASF-1), Iraqi isolate, general characteristics, antibiotic susceptibility tests, curing, plasmid profile.