title: Discrimination of Aspergillus isolates at the species and strain level by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry fingerprinting.
abstract: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was used to generate highly reproducible mass spectral fingerprints for 12 species of fungi of the genus Aspergillus and 5 different strains of Aspergillus flavus. Prior to MALDI-TOF MS analysis, the fungi were subjected to three 1-min bead beating cycles in an acetonitrile/trifluoroacetic acid solvent. The mass spectra contain abundant peaks in the range of 5 to 20kDa and may be used to discriminate between species unambiguously. A discriminant analysis using all peaks from the MALDI-TOF MS data yielded error rates for classification of 0 and 18.75% for resubstitution and cross-validation methods, respectively. If a subset of 28 significant peaks is chosen, resubstitution and cross-validation error rates are 0%. Discriminant analysis of the MALDI-TOF MS data for 5 strains of A. flavus using all peaks yielded error rates for classification of 0 and 5% for resubstitution and cross-validation methods, respectively. These data indicate that MALDI-TOF MS data may be used for unambiguous identification of members of the genus Aspergillus at both the species and strain levels.
authors.affiliation: Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Health Effects Laboratory Division, Morgantown, WV 26505, USA. jhettick@cdc.gov
authors.forename: Justin M
authors.initials: JM
authors.lastname: Hettick
authors.forename: Brett J
authors.initials: BJ
authors.lastname: Green
authors.forename: Amanda D
authors.initials: AD
authors.lastname: Buskirk
authors.forename: Michael L
authors.initials: ML
authors.lastname: Kashon
authors.forename: James E
authors.initials: JE
authors.lastname: Slaven
authors.forename: Erika
authors.initials: E
authors.lastname: Janotka
authors.forename: Francoise M
authors.initials: FM
authors.lastname: Blachere
authors.forename: Detlef
authors.initials: D
authors.lastname: Schmechel
authors.forename: Donald H
authors.initials: DH
authors.lastname: Beezhold
mesh_terms: D001230:Aspergillus / Q000145:classification* / Q000302:isolation & purification; D001231:Aspergillus flavus / Q000145:classification / Q000302:isolation & purification; D016000:Cluster Analysis; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*