FIG. 4.

Characteristic masses (in daltons) recognized as markers for the identification of P. agglomerans, P. vagans, P. ananatis, and P. dispersa. Two or more masses are considered equivalent and are shown on the same line if their values deviate by less than 800 ppm from the average. The 800-ppm mass accuracy setting defining the spectral bin size was evaluated/validated by AnagnosTec GmbH. Even if the error margin in a data set analyzed on a single MALDI-TOF MS instrument is usually smaller (around 400 ppm), a larger bin size is necessary to allow, within the SARAMIS database, the comparison of data collected with different instruments in different laboratories. An 800-ppm mass accuracy still allows one to distinguish mass differences of 14 Da for proteins of 10 kDa, which is normally sufficient to detect single-amino-acid exchanges in proteins of that size. Masses shared by three or more Pantoea species are marked in bold.