Siderotyping of fluorescent Pseudomonas: molecular mass determination by mass spectrometry as a powerful pyoverdine siderotyping method.

The numerous pyoverdines so far characterized as siderophores of fluorescent Pseudomonas could be usually differentiated one from each others by the two physico-chemical and physiological methods of siderotyping, i.e., siderophore-isoelectrofocusing and siderophore-mediated iron uptake. As shown in the present paper, the structural diversity of the peptide chain characterizing these molecules results in a very large panel of molecular masses representing 64 different values ranging from 889 to 1,764 Da for the 68 compounds included in the study, with only a few structurally different compounds presenting an identical molecular mass. Thus, the molecular mass determination of pyoverdines through mass spectrometry could be used as a powerful siderotyping method.