A combined meta-barcoding and shotgun metagenomic analysis of spontaneous wine fermentation

Wine is a complex beverage, comprising hundreds of metabolites produced through the action of yeasts and bacteria in fermenting grape must. To ensure a robust and reliable fermentation, most commercial wines are produced via inoculation with commercial strains of the major wine yeast, Saccharomyces cerevisiae. However, there is a growing trend towards the use of uninoculated or \"wild\" fermentations, in which the yeasts and bacteria that are naturally associated with the vineyard and winery, perform the fermentation. In doing so, the varied metabolic contributions of the numerous non-Saccharomyces species in this microbial community are thought to impart complexity and desirable taste and aroma attributes to wild ferments in comparison to their inoculated counterparts.\n\nIn order the map the microflora of spontaneous fermentation, metagenomic techniques were used to characterize and monitor the progression of fungal species in several wild fermentations. Both amplicon-based ITS phylotyping (meta-barcoding) and shotgun metagenomics were used to assess community structure. While providing a sensitive and highly accurate means of characterizing the wine microbiome, the shotgun metagenomic data also uncovered a significant over-abundance bias in the ITS phylotyping abundance estimations for the common non-Saccharomyces wine yeast genus Metschnikowia.