PNNL

Abstract

The capability for rapid and accurate identification of microorganisms has potential applications that would include the monitoring of industrial bioprocessing operations, food safety analyses, disease diagnosis, and the detection of potential biological hazards. Efforts based upon matrix assisted laser desorption ionization mass spectrometry (MALDI-MS) to detect and identify specific microorganisms have been actively pursued for several years. We report a new method being developed to select useful biomarkers for the identification of microorganisms based upon electrospray ionization (ESI)-ion trap mass spectrometry. Crude cell lysates are processed using a recently developed dual microdialysis device and then directly infused into an ion trap MS. The low ESI flow rate and precursor ion accumulation capability of the ion trap MS enables high sensitivity MS/MS analyses. Precursor ions were automatically selected and analyzed using tandem MS (MS/MS) to produce a "global" MS/MS surveys, for two-dimensional data displays. Such global MS/MS surveys are demonstrated for Escherichia coli lysates. The distinctive MS/MS spectral patterns can be used to identify mass spectrometric signals useful as biomarkers, which then provide a basis for microorganism identification. The results presented here show the application of this method for the identification of microorganisms, as well as for detection of bacteriophage MS2 in the presence of a large excess of Escherichia coli.