Evaluation of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for differentiation of Pichia kluyveri strains isolated from traditional fermentation processes.

Rationale: Non-Saccharomyces yeasts are widespread microorganisms that nowadays have gained importance for their ability to produce volatile compounds which in alcoholic beverages improve aromatic complexity and therefore the overall quality. Their rapid identification and differentiation in fermentation processes is vital for timely decision making.

Methods: A total of 19 strains of Pichia kluyveri isolated from mezcal, tejuino and cacao fermentations were analyzed with rep-PCR fingerprinting using the primer (GTG) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) on a Microflex LT mass spectrometer using Biotyper 3.1 software (Bruker Daltonics).

Results: The comparative analysis between MS spectra and rep-PCR patterns obtained from these strains showed a high similarity between both methods. However, minimal differences between the obtained rep-PCR and MALDI-TOF MS clusters could be observed, especially by the presence and/or absence of one or more discriminating peaks even when they have similarities in their main spectra projection, observing that isolates from the same fermentative process were grouped into the same sub-cluster based on their MALDI-TOF MS profiles.

Conclusions: The data shown suggests that MALDI-TOF MS is a promising alternative technique for rapid, reliable and cost-effective differentiation of native yeast strains isolated from different traditional fermented foods and beverages.