FINGERPRINT MATCHING OF E-COLI STRAINS WITH MATRIX-ASSISTED-LASER-DESORPTION IONIZATION TIME-OF-FLIGHT MASS-SPECTROMETRY OF WHOLE CELLS USING A MODIFIED CORRELATION APPROACH

We have developed a mathematical algorithm to compare and distinguish matrix-assisted laser desorption/ ionization (MALDI) mass spectra of w hole bacteria cells. This fingerprint matching technique eliminates th e subjectivity involved in visually comparing two spectra to determine whether they match and it provides a quantitative measure of spectral similarity. Using it, we have distinguished twenty five different str ains of a single bacteria species, E. coli. Cells are grown in culture , samples are prepared, and MALDI-TOF mass spectra are recorded for ea ch strain. Pairs of spectra are compared by a modified cross correlati on procedure. This modified approach increases the sensitivity of corr elation analysis to small spectral differences. The technique can be f ine-tuned by varying the number of intervals into which spectra are di vided. (C) 1998 John Wiley & Sons, Ltd.