Document Type : Research Paper
Author
University Of ALanbar - College of Dentistry
Abstract
Bacteria Pseudomonas aurginosa, E coli and Stapthylococcus aureus were exposure to different doses of ultraviolet radiation and survival curves drawn for each type, the results show that the bacteria Pseudomonas aurginosa more resistant by UV radiation than Ecoli and Stapthylococcus aureus bacteria. The bacterium Pseudomonas aeruginosa was irradiated with different doses of U.V light via wave length( 254 nm ) for different periods ( 50 , 100 , 150 , and 200 sec ) .It appear that part of irradiated bacterial culture was exposed to sun light and the other part was kept in the dark . The survivors of the cells exposed to the sun light was more than the dark and this ensure possessing the bacterium photoreactivating repair system investigate the excision repair system, the minimal inhibitory concentration ( MIC) of caffeine against bacteria was studied by exposing the bacterium to different concentrations of caffeine (10 , 15 , 20 and 25 mg/ml ) and the MIC was 20 mg/ml , Furthermore the bacterium was exposed to different times of U.V. light in the presence of caffeine and the studying ensure that the survivors of the cells in the medium with caffeine was less than the medium with absence of caffeine and this leads to possess the bacterium excision repair system. To detect the recombination repair system , the bacterium was exposed to the concentrations( 0.1 ,0.2 , 0.3 , 0.4 μg / ml) of acrivlavine and the MIC was 0.3 μg / ml , then the bacterium was exposed to different times of U.V. light in the presence of acrivlavine . The survivors of the cells in the medium with acrivlavine was less compared with the absence of acrivlavine. It would seem that possessing bacterium recombination repair system . sensitivity test of the bacterium against antibiotics was established and the results appeare that it was to the antibiotics Chloramphenicol, Carpencillin, Trimethoprim, Rifampicin The diameters of inhibition were (16,20,17,18) mm respectively and resistant to the antibiotics Amoxicillin, Ampicillin, Clindomycin, Cloxacillin , Nalidixic acid , Cephaloxin , Tetracyclin and Tobromycin. To study SOS repair system the bacterium was mutated with direct mutagens represented with nitrous acid and indirect mutagens represented with U.V. light to isolate Rifampicin and Chloramphenicol mutants. It is quite likely that the sensitivity of bacterium for mutagenesis then possessing SOS repair system .
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