Patent ID: 8071329

Claim:
A method of analyzing or identifying single cell organisms or microorganisms, comprising the steps of: preparing a sample of at least one single cell organism or microorganism on a matrix assisted laser desorption ionization (MALDI) sample holder; adding an acid solvent to said sample on the MALDI sample holder to extract selectively a reproducible set of acid soluble proteins from the sample, said acid selected from the group consisting of trifluoroacetic acid, acetic acid, and formic acid; drying the sample extracted acid soluble proteins on the MALDI sample holder; digesting the reproducible set of acid soluble proteins in situ on said MALDI sample holder with a buffered proteolytic enzyme or with a chemical reagent that cleaves said proteins at specific residues, to produce peptide fragments in situ on the sample holder, where said digesting step is carried out for a time period of from 1 to 25 minutes; subjecting the peptide fragments on the MALDI sample holder to mass spectrometry and tandem mass spectrometric analysis to obtain mass spectra corresponding to said peptide fragments; determining at least partial sequences of at least some of the peptide fragments from said mass spectra; and identifying said acid soluble proteins and thus the single cell organism or microorganism by comparison to information in databases either constructed by analysis of pure microorganisms or constructed in silico from gene and protein sequences.