ABSTRACT

 Mutation is a very important concept in biology today that leads to variations in genes. A mutation is a permanent alteration in the sequence of nitrogenous bases of a DNA molecule. The result of a mutation is generally a change in the end-product specified by that gene. In some cases, a mutation can be beneficial if a new metabolic activity arises in a microorganism, or it can be detrimental if a metabolic activity is lost. Mutations can be spontaneous, or induced by a mutagen in the environment. Mispairing is probably mostly due to cellular processes such as Tautomeric shift of bases, oxi'dative damage to DNA, Depurination and Deamination or caused by "environment", i.e chemical radiation viruses, diet and lifestyle (Mutagens). Substitution of a nucleotide and Deletion or addition of them is two mechanisms of mutation. Mutation in bacteria has done lethal mutation. IdentIfying the these mutations requires detection methods. Classic methods i,e, Replica plating, Penicillin enrichment, Ames test, Use of chromogenic substrate and novel tests such as Polymerase chain reaction (PCR) and Gel electrophoresis, Gene probes and Southern blotting, DNA sequencing and DNA microarray are some of these methods that are highlighted in this review. The UV radiations have become an effective way for the sake of solving all problems related to environmental contamination. Tests are carried on the following microorganisms: Serratla sp, Kiebsiella pneumonIa, staphyoloccus aureus, pseudomonas aeruginosae, Escherichia coli,, Vibrio sp, Streptococcus sp, Salmonella sp, Shigella sp, Bacillus sp. The cultures were irradiated with UV. The selected distances are 1 and 5 cm and the exposure time was 5s, lOs, 15s, 3Os to SOs. All treatments are carried out hi a dark chamber. Further, the control group is prepared in lthe same conditions except that a sterile cover hides half of the seeded plate. The extennination of most microorganisms has been view due to the combined effect of time and the exposure distance. The time of 60s and a distance of 1 cm was the best combination to achieve the total cessation of growth of the bacteria studied.