Desorption electrospray ionization mass spectrometry of intact bacteria.
Desorption electrospray ionization (DESI) mass spectrometry (MS) was used to differentiate seven bacteria species on the basis of their measured DESI-mass spectral profile. Both gram-positive and gram-negative bacteria were tested and included Escherichia coli, Staphyloccocus aureus, Enterococcus sp., Bordetella bronchiseptica, Bacillus thuringiensis, Bacillus subtilis and Salmonella typhimurium. Distinct DESI-mass spectra, in the mass range of 50-500 u, were obtained from whole bacteria in either positive or negative ion modes in less than 2 mins analysis time. Positive ion DESI-mass spectral fingerprints were compared using principal components analysis (PCA) to investigate reproducibility for the intraday and the day-to-day measurements and the method selectivity to differentiate the bacteria studied. Detailed study of variances in the assay revealed that a large contribution to the DESI-mass spectral fingerprint variation was the growth media preparation procedure. Specifically, experiments conducted with the growth media prepared using the same batch yielded highly reproducible DESI-mass spectra, both in intraday and in day-to-day analyses (i.e. one batch of growth media used over a 3-day period versus a new batch every day over the same 3-day period). Conclusions are drawn from our findings in terms of strategies for rapid biodetection with DESI-MS.
Meetani
Mohammed A
MA
Department of Chemistry, Faculty of Science, United Arab Emirates University, Al Ain, United Arab Emirates.
Shin
Yong-Seung
YS
Zhang
Shaofeng
S
Mayer
Richard
R
Basile
Franco
F
D001426:Bacterial Proteins / Q000032:analysis*; D006090:Gram-Negative Bacteria / Q000378:metabolism*; D006094:Gram-Positive Bacteria / Q000378:metabolism*; D020543:Proteome / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization
D001426:Bacterial Proteins; D020543:Proteome