It has been well elucidated that bacterial adaptation to certain stresses leads to a modification of the membrane fatty acid (FA) composition. In this context, an analysis of the GA composition of Pseudomonas aeruginosa after adaptation to UVC radiation was performed. The different phospholipid fractions were separated by Thin Layer Chromatography (TLC) and the GA composition was determined by gas chromatography (GC). Three major phospholipid classes were identified. The study by gas chromatography (GC) of the GA composition of total phospholipids and of three phospholipid classes PE, PG and Cd showed that the transition from the exponential phase to the stationary phase is reflected in the total lipids by an increase in the unsaturation index. Regarding the effect of UVc on FA composition, our results revealed a notable alteration of FAs after UV adaptation, with an increase in unsaturation index. In conclusion, we suggest that the alteration of GA composition ensures adequate membrane fluidity for Pseudomonas survival following UVc exposure.