Strain-level bacterial identification by CeO2-catalyzed MALDI-TOF MS fatty acid analysis and comparison to commercial protein-based methods

Sci Rep. 2015 Jul 20:5:10470. doi: 10.1038/srep10470.

Abstract

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has emerged as a rapid approach for clinical bacterial identification. However, current protein-based commercial bacterial ID methods fall short when differentiating closely related species/strains. To address this shortcoming, we employed CeO2-catalyzed fragmentation of lipids to produce fatty acids using the energy inherent to the MALDI laser as a novel alternative to protein profiling. Fatty acid profiles collected from Enterobacteriaceae, Acinetobacter, and Listeria using CeO2-catalyzed metal oxide laser ionization (MOLI MS), processed by principal component analysis, and validated by leave-one-out cross-validation (CV), showed 100% correct classification at the species level and 98% at the strain level. In comparison, protein profile data from the same bacteria yielded 32%, 54% and 67% mean species-level accuracy using two MALDI-TOF MS platforms, respectively. In addition, several pathogens were misidentified by protein profiling as non-pathogens and vice versa. These results suggest novel CeO2-catalyzed lipid fragmentation readily produced (i) taxonomically tractable fatty acid profiles by MOLI MS, (ii) highly accurate bacterial classification and (iii) consistent strain-level ID for bacteria that were routinely misidentified by protein-based methods.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacteria / classification*
  • Bacteria / metabolism*
  • Bacterial Proteins / metabolism
  • Catalysis
  • Cerium*
  • Fatty Acids / metabolism*
  • Metabolomics / methods
  • Proteomics / methods
  • Reproducibility of Results
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization* / methods

Substances

  • Bacterial Proteins
  • Fatty Acids
  • Cerium
  • ceric oxide