Description:This book contains chapters from participants in a recent symposium, organized by the Division of Analytical Chemistry during the ACS National Meeting in Washington DC in August, 2009, as well as several other active researchers in the field. The book covers aspects of mass spectrometry (MS) applications for microorganism characterization in several fields: biodefense, clinical diagnostics, food safety, environmental monitoring, and chemotaxonomy/biosystematics. The diverse list of contributors - from academia, government as well as industry present multi-faceted and broad perspectives on the subject to be presented.