title: Instrumental improvements and sample preparations that enable reproducible, reliable acquisition of mass spectra from whole bacterial cells.
abstract: BACKGROUND
  Rapid sub-species characterization of pathogens is required for timely responses in outbreak situations. Pyrolysis mass spectrometry (PyMS) has the potential to be used for this purpose.
  
  
  METHODS
  However, in order to make PyMS practical for traceback applications, certain improvements related to spectrum reproducibility and data acquisition speed were required. The main objectives of this study were to facilitate fast detection (<30 min to analyze 6 samples, including preparation) and sub-species-level bacterial characterization based on pattern recognition of mass spectral fingerprints acquired from whole cells volatilized and ionized at atmospheric pressure. An AccuTOF DART mass spectrometer was re-engineered to permit ionization of low-volatility bacteria by means of Plasma Jet Ionization (PJI), in which an electric discharge, and, by extension, a plasma beam, impinges on sample cells.
  
  
  RESULTS
  Instrumental improvements and spectral acquisition methodology are described. Performance of the re-engineered system was assessed using a small challenge set comprised of assorted bacterial isolates differing in identity by varying amounts. In general, the spectral patterns obtained allowed differentiation of all samples tested, including those of the same genus and species but different serotypes.
  
  
  CONCLUSIONS
  Fluctuations of ±15% in bacterial cell concentrations did not substantially compromise replicate spectra reproducibility.
authors.affiliation: Innovative Safety Technologies Branch, Systems Biology Div., National Center for Toxicological Research, Food Drug Administration, Jefferson, AR, USA.
authors.forename: Pierre
authors.initials: P
authors.lastname: Alusta
authors.affiliation: Innovative Safety Technologies Branch, Systems Biology Div., National Center for Toxicological Research, Food Drug Administration, Jefferson, AR, USA.
authors.forename: Dan
authors.initials: D
authors.lastname: Buzatu
authors.affiliation: Innovative Safety Technologies Branch, Systems Biology Div., National Center for Toxicological Research, Food Drug Administration, Jefferson, AR, USA.
authors.forename: Anna
authors.initials: A
authors.lastname: Williams
authors.affiliation: Innovative Safety Technologies Branch, Systems Biology Div., National Center for Toxicological Research, Food Drug Administration, Jefferson, AR, USA.
authors.forename: Willie-Mae
authors.initials: WM
authors.lastname: Cooper
authors.affiliation: University of Arkansas at Little Rock, Department of Biology, Little Rock, AR, USA.
authors.forename: Olga
authors.initials: O
authors.lastname: Tarasenko
authors.affiliation: Innovative Safety Technologies Branch, Systems Biology Div., National Center for Toxicological Research, Food Drug Administration, Jefferson, AR, USA.
authors.forename: R Cameron
authors.initials: RC
authors.lastname: Dorey
authors.affiliation: Bionetics Corp., National Center for Toxicological Research, Food Drug Administration, Jefferson, AR, USA.
authors.forename: Reggie
authors.initials: R
authors.lastname: Hall
authors.affiliation: Department of Chemistry, University of Texas, Austin, TX, USA.
authors.forename: W Ryan
authors.initials: WR
authors.lastname: Parker
authors.affiliation: Innovative Safety Technologies Branch, Systems Biology Div., National Center for Toxicological Research, Food Drug Administration, Jefferson, AR, USA.
authors.forename: Jon G
authors.initials: JG
authors.lastname: Wilkes
mesh_terms: D001419:Bacteria / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification*; D015373:Bacterial Typing Techniques / Q000191:economics / Q000295:instrumentation / Q000379:methods*; D013058:Mass Spectrometry / Q000191:economics / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D013048:Specimen Handling