Lysine decarboxylases (Ldc) are widely distributed enzymes that catalyse the decarboxylation of L-lysine to form cadaverine, a natural polyamine playing a key role in a wide range of physiological process. The Gram-negative bacterium Francisella tularensis is the etiological agent of tularemia. A previous report showed that F. novicida transposon mutant with insertions in cadA (FTT0406) which encodes a putative lysine decarboxylase (herein designed as LdcF) was attenuated in mouse spleen. Here, to address the role of this protein, we compared the proteomes of bacterial strains expressing or not LdcF.