Differentiation of Bacteria Using Lipid Profiles from MALDI-MS

by Gidden, Jennifer; Denson, Jackie; Liyanage, Rohana; Ivey, D. Mack; Lay, Jackson O., Jr.

The success of mass spectrometry in the rapid anal. of microorganisms is based primarily on its high specificity and sensitivity, which lead to the ability to differentiate organisms by detection of specific biomarkers or fingerprint patterns. Several groups have shown that MALDI-MS can be used to identify bacteria based on peptide/protein profiles in the mass spectra. Another method of identifying bacteria involves the detn. of its lipid profile. This method has the added bonuses (and complications) of being able to monitor such things as environmental changes, growth conditions, metab. mechanisms, and membrane structure simply by following the accompanying changes in lipid compn. In other words, lipid profiles reflect both taxonomy and cellular biochem. Work in this area typically uses pyrolysis or FAMES followed by GC-MS anal. to det. the fatty acid content and then use this data for taxonomic classification. However, in recent years, MALDI-MS and ESI-MS have been used to det. lipid content by focusing on intact triacylglycerols or phospholipids, which may give a more complete picture of cellular lipidomics. In this talk, we will discuss the use of MALDI-TOF mass spectrometry to characterize bacteria. Our data will focus on the effects of taxonomy, cellular environment and methodol. on bacterial spectra. Current results indicate that different bacterial species can be easily distinguished based on different phospholipid profiles detected in crude exts. by MALDI-TOF MS. However, before these results can be extrapolated to more general applications in bacterial taxonomy a much larger no. of bacterial will need to be characterized.