Effects of gamma radiations on some aspects of the biology of salmonella

This work aimed at the study of the effect of gamma radiation on certain aspects of the biology of Salmonella, few works joined this type and gamma radiations. The lethal effect of ionizing radiations was associated at other bacterial types, to an oxidative stress due to the presence of reactive spices of oxygen and leading to deteriorations of membrane cells, proteins and nucleic acids.Thus, we proceeded to an analysis of the viability of four Salmonella serovars subject to different radiation doses going from 0.5 to 2 KGy. The results showed a viability reduction dose dependent with a differential behavior, statistically significant. In order to detect possible radio induced changes at the restriction site of the enzymes XbaI and BlnI usually used for the typing of Salmonella, we carried out a DNA restriction profile analyse of the four serovars by pulsed filed gel electrophoresis. The results showed that no change appeared on the level of these restriction sites for the used enzymes following an irradiation of 2KGy. The study of the sensitivity of Salmonella to antibiotics after a gamma radiation showed that gamma radiation has increased the sensitivity of Salmonella isolates to porin associated antibiotics. Statistical analyses showed that the effect of different irradiation dose treatment on the antibiotic sensitivity is increasingly significant. The irradiation didn't induce modifications of the sensitivity to other antibiotics, probably because of their nature, of their penetration mode inside the cell or their action way. To tray to explain the differential behavior of different serovars to irradiation. We analyzed by Quantitative real time PCR (RT- PCR), the expression level of the ARNm of the genes KATN (catalase non-hemique), DNAK (protein of thermal shock), RNA polymerase as well as of the 16S rRNA. The results showed either a repression or an induction of certain genes under the effect of an irradiation of 2 KGy. (Author)