FT-IR spectroscopy: A powerful tool for studying the inter- and intraspecific biodiversity of cultivable non-Saccharomyces yeasts isolated from grape must.

The efficiency of the FT-IR technique for studying the inter- and intra biodiversity of cultivable non-Saccharomyces yeasts (NS) present in different must samples was examined. In first, the capacity of the technique FT-IR to study the global diversity of a given sample was compared to the pyrosequencing method, used as a reference technique. Seven different genera (Aureobasidium, Candida, Cryptococcus, Hanseniaspora, Issatchenkia, Metschnikowia and Pichia) were identified by FT-IR and also by pyrosequencing. Thirty-eight other genera were identified by pyrosequencing, but together they represented less than 6% of the average total population of 6 musts. Among the species identified, some of them present organoleptic potentials in winemaking, particularly Starmerella bacillaris (synonym Candidazemplinina). So in a second time, we evaluated the capacity of the FT-IR technique to discriminate the isolates of this species because few techniques were able to study intraspecific NS yeast biodiversity. The results obtained were validated by using a classic method as ITS sequencing. Biodiversity at strain level was high: 19 different strains were identified from 58 isolates. So, FT-IR spectroscopy seems to be an accurate and reliable method for identifying major genera present in the musts. The two biggest advantages of the FT-IR are the capacity to characterize intraspecific biodiversity of non-Saccharomyces yeasts and the possibility to discriminate a lot of strains.