Oenological phenomes of lachancea thermotolerans reflect patterns of domestication and alloptric differentiation

The yeast Lachancea thermotolerans (ex. Kluyveromyces thermotolerans) can positively contribute to the acidity and aroma profile of fermented beverages such as wine. This common constituent of the grape/wine microbiota also occupies a range of natural habitats worldwide. The differentiation in the L. thermotolerans population is driven by geographic determination and ecological niche, as revealed by our recently-developed 14-microsatellite method. The natural isolates are grouped based on their geographic origin, whereas clustering of anthropic (in particular oenological) isolates suggests domestication events within the species. To determine whether, and to what extent, the strains differ in oenological traits and harbour signatures of domestication and/or local divergence, 94 previously genotyped strains were characterised in Vitis vinifera cv. Chardonnay fermentations. The extensive dataset comprised microbial growth and fermentation kinetics parameters, production of primary and secondary metabolites and the resultant (de)acidification, i.e. 114 measured/derived parameters for triplicate fermentations. The common oenological features of L. thermotolerans strains were their glucophilicity, relatively extensive fermentation ability (7.3% v/v ethanol), low production of acetic acid and formation of lactic acid. A seven-fold variation was observed in concentration of lactate, significantly affecting the pH of the wines, which ranged between 3.16 - 3.81. An untargeted analysis of volatile compounds revealed that 58 out of 90 volatiles were affected at an L. thermotolerans strain level. Linear discriminant analysis performed using the obtained metabolic dataset showed the separation of L. thermotolerans genetic groups driven by distinct fermentation performance and production of (non)-volatile metabolites. Together, these results provided a population-wide insight into the extent of phenotypic variability in oenologically-relevant traits in L. thermotolerans, whilst adding support for the occurrence of domestication events and allopatric differentiation within this remarkable yeast species.