MALDI-TOF mass spectrometry-based identification of Eurotiales from different substrates and locations in Brazil

Abstract

We used matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) fingerprinting to identify 95 strains of Aspergillus, Penicillium, and Talaromyces isolated from soil, marine sediment, and plants in Brazil. Samples for mass spectrometry were composed of conidia and conidiophores directly applied to the target plate and co-crystallized with the matrix solution. Cluster analyses of MS data and phylogenetic analyses based on the second largest subunit of RNA polymerase II gene sequence (RPB2) supported the identification of 42 species in Aspergillus (n = 17), Penicillium (n = 16), and Talaromyces (n = 9). In few cases, MALDI-TOF dendrograms split strains from one species into two neighboring clusters, but strains from different species were never grouped together. Three Penicillium species delimited by MALDI-TOF MS did not correspond to known species present in the large RPB2 dataset available for this group and may represent new taxa. These results expand the scope of applications of MALDI-TOF MS to the task of screening phylogenetically diverse assemblages of morphologically similar strains derived from field collections, allowing for fast discrimination of common and rare species, and detection of possible new taxa.