Abstract
This study was carried out to explore the adaptive mechanisms of Salmonella enterica serovar Typhimurium, in particular the implication of fatty acids (FA) in the remodeling of membrane lipid composition to overcome the combined effects of long-term starvation and gamma-irradiation stresses. In addition, cell surface hydrophobicity was also evaluated. The bacterial strains (control and starved) were treated with a nonlethal gamma-irradiation dose of 0.5 kay and sublethal doses of 1 kGy. Gas chromatography analysis showed that the FA composition of starved and gamma-irradiated cells was modified. However starvation combined with gamma-irradiation induced more modifications in the FA composition than gamma-irradiation or starvation alone. Indeed, the unsaturated FA-to-saturated FA ratio decreased significantly for both strains compared with gamma-irradiated cells, as main consequence of the cyclic FA formation. Our results showed that starvation, irradiation, or combined stresses significantly influenced the hydrophobicity, and this may have affected the virulence state of Salmonella Typhimurium cells. This study represents one of the few to demonstrate the modifications on bacterial membrane as a cellular response to survive to the ionizing radiation combined with long-term starvation stress.