Direct bacteria analysis using laserspray ionization miniature mass spectrometry.

An atmospheric pressure laserspray ionization mass spectrometry (AP-LSI mini MS) has been developed and employed in the fast analysis of bacteria. Without using surfactants or any extracting methods, 21 foodborne bacteria from 12 genera were directly analyzed. Typical fingerprints of small molecules and lipids were detected and recognized in the mass spectra with high reproducibility. Furthermore, a supervised multivariate statistics method, orthogonal partial least squares (OPLS), was applied, and these bacteria could be differentiated at both genus and species levels. With improved performance in the future, AP-LSI mini MS could be a simple, effective, and fast approach for direct bacteria analysis on the field.