Mass spectral investigations on microorganisms

Bacterial cells undergo lysis readily, when suspended in mild aqueous acids, and release the cellular proteins along with other biomolecules. Molecular masses of the protein biomarkers released in-situ from individual intact bacterial cells could be directly measured by mass spectrometry. Limited sample clean up may be required at times, prior to mass spectral analysis, to remove any ionizable impurities such as salts, buffers and deergents. The marker proteins specific for individual genus, species and strains were determined by the comparison of the biomarkers measured for several closely related organisms. Even though there is a probability of over 4000 cellular proteins expressed in any single bacterial cell, only a small fraction of the projected marker proteins are identified consistently during the process. This could be due to the variation in the ionization properties of the proteins and the limited energy available to prompt their ionization. Variation in the sample processing and culture condit...