MALDI-TOF MS as a tool to identify foodborne yeasts and yeast-like fungi
(2018) International Journal of Food Microbiology — Vol. 266, p. 109-118 (2018)
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- Abstract
- Since food spoilage by yeasts causes high economic losses, fast and accurate identifications of yeasts associated with food and food-related products are important for the food industry. In this study the efficiency of the matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) to identify food related yeasts was evaluated. A CBS in-house MALDI-TOF MS database was created and later challenged with a blinded test set of 146 yeast strains obtained from food and food related products. Ninety eight percent of the strains were correctly identified with log score values > 1.7. One strain, Mrakia frigida, gained a correct identification with a score value < 1.7. Two strains could not be identified at first as they represented a mix of two different species. These mixes were Rhodotorula babjevae with Meyerozyma caribbica and Clavispora lusitaniae with Debaryomyces hansenii. After separation, all four species could be correctly identified with scores > 1.7. Ambiguous identifications were observed due to two incorrect reference mass spectra's found in the commercial database BDAL v.4.0, namely Candida sake DSM 70763 which was re-identified as Candida oleophila, and Candida inconspicua DSM 70631 which was re-identified as Pichia membranifaciens. MALDI-TOF MS can distinguish between most of the species, but for some species complexes, such as the Kazachstania telluris and Mrakia frigida complexes, MALDI-TOF MS showed limited resolution and identification of sibling species was sometimes problematic. Despite this, we showed that the MALDI-TOF MS is applicable for routine identification and validation of foodborne yeasts, but a further update of the commercial reference databases is needed.
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Quintilla, R., Kolecka, A., Casaregola, S., Daniel, H.-M., Houbraken, J., Kostrzewa, M., Boekhout, T., & Groenewald, M. (2018). MALDI-TOF MS as a tool to identify foodborne yeasts and yeast-like fungi. International Journal of Food Microbiology, 266, 109-118. https://doi.org/10.1016/j.ijfoodmicro.2017.11.016 (Original work published 2018)