Genetic diversity of Saccharomyces cerevisiae isolates from organic Pinot noir wine production in New Zealand

Saccharomyces cerevisiae is the major yeast species involved with the production of alcoholic fermented beverages, including wine which is a major export commodity. The species exhibits significant interstrain diversity, which influences the character of wines produced. Spontaneous fermentation is an uncommon production method, but such organic approaches are increasing in consumer appeal. However, the level of interstrain diversity in such production systems is infrequently characterised, yet the influence of individual strains on the organoleptic character of wine is well recognised. We used a DNA-based Inter-Delta Typing (IDT) method to elucidate the genetic diversity and population dynamics of Saccharomyces cerevisiae isolates from an organic Pinot Noir winemaker in Waipara, Aotearoa New Zealand. One hundred and forty-three S. cerevisiae isolates from key fermentation stages during the production of organic Pinot noir wines produced by spontaneous fermentation were differentiated by IDT analysis into 95 different genotypes, of which 21 were observed more than once. Three IDT genotypes were observed among each of the fermentation stages yielding isolates, although none individually reached a position of dominance. The diversity observed may reflect both the biodynamic nature of the organic production system, including climatic factors, as well as the relative stage of maturity of the New Zealand wine industry compared with the global winemaking landscape. The impact of this diversity on the organoleptic properties of wine produced in this region using organic, spontaneous fermentation approaches requires further study. The value of IDT to characterise the genetic diversity of S. cerevisiae is supported, and may have value in identifying strains of particular significance. • First known analysis of S. cerevisiae genetic diversity in organic NZ viticulture. • Genotypic diversity was in the higher range of those reported internationally. • Results may reflect differences in climatic variation or industrial maturity.