MALDI-TOF MS based identification of food-borne yeast isolates

• Identification of yeasts by MALDI-TOF MS and conventional assays was compared
• ITS-sequencing was used as gold standard
• MALDI-TOF MS is a reliable method for identification of food-borne yeasts
• Update of MALDI-TOF MS databases decreased the portion of not identifiable isolates

In this study, food-borne yeast isolates (n = 96), comprising at least 33 species, were identified using MALDI-TOF MS and conventional methods (API ID 32 C and Phoenix Yeast ID). Discrepancies of both methods were resolved by sequencing the ITS1–5.8S–rRNA–ITS2 region. For ten isolates, mainly classified to Rhodotorula and Trichosporon species, no clear final species identification was possible. 62 isolates were correctly identified to species level using either MALDI-TOF MS or conventional tests. 15 isolates were misidentified when applying conventional assays. In contrary, no species misidentifications were observed after MALDI-TOF MS based classification. In return, 16 isolates were not identifiable after matching their protein fingerprints against MALDI Biotyper 4.0.0.1 library. MALDI TOF MS in-house database update clearly improved the identification. In conclusion, the presented data suggest that MALDI-TOF MS is an appropriate platform for reliable classification and identification of food-borne yeast isolates.