Characteristic peak shifts used for strain characterization and MALDI-Types definition. The 24 average spectra are plotted, corresponding to all except one sequenced isolates. Intensity varies from 200 to 1000. The RpmC IF4 (strain NAC SLCC MFF) is present but partially masked by a stronger peak shared by the other 23 isolates. The central figure displays 3 different biomarkers that correspond to 5 different peaks. The first at 10 300 m/z is shared by all isolates in our collection and corresponds to RpsS (species biomarker). The two peaks in the middle correspond to RpsN and the last two peaks correspond to RpsO, isoforms 1 and 2 respectively.