| Abstract: |
Traditional fermented beverages are a value in the global artisanal market huge repository of microbial diversity of historical importance, which are underpinned by complex and interacting communities of yeast and bacteria. The exact taxonomic identification of these yeasts is not only an academic task but is also a key step to understanding the ecology of fermentation, the improvement of industrial starter cultures, the safety of the products in the presence of more virulent spoilage organisms and the maintenance of distinctive organoleptic properties of local fermented products. This review report critically discusses the evolution and the status of yeast identification methods, including the traditional culture-based method and the old nucleic acid extraction procedures, as well as new and emerging automated systems. A detailed comparative study is performed between the bioMérieux VITEK 2 Compact system and the bioMérieux RapID Yeast Plus system and high-resolution genotypic techniques such as ITS and D1/D2 domain sequencing that can distinguish cryptic species complexes. In addition, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) is thoroughly explored as a disruptive and paradigm shifting proteomic technology. This report shows that, in spite of the potential of automated phenotypic systems for fast clinical diagnosis, the value of these systems is severely restricted in the case of the environmentally stressed, highly phenotypic yeast strains typical of traditional fermented drinks. Finally, a polyphasic taxonomic strategy combining genomic accuracy with the proteomic rapidity and biochemical profiling is established as the gold standard for yeast robust characterization in food and beverage microbiology. |
