Investigating the biochemical and fermentation attributes of Lachancea species and strains: Deciphering the potential contribution to wine chemical composition.

Yeasts of various genera are increasingly used alongside Saccharomyces cerevisiae to drive wine fermentations owing to their positive contribution to the organoleptic profile of the resulting wines. One such yeast species is Lachancea thermotolerans. Other species of the genus Lachancea, namely, L. fermentati and L. lanzarotensis have also been isolated from the fermentation environment, but have not received the same degree of attention as L. thermotolerans. The aim of this study was to investigate the oenological potential of these three Lachancea species, regarding their expression of oenologically relevant enzymes, their fermentation attributes and the expression and location of β-glucosidase during fermentation of synthetic and real grape must (Muscat of Alexandria). In the current study we evaluated three species viz. L. thermotolerans (14 strains), L. fermentati (1 strain) and L. lanzarotensis (2 strains). Our data show that all the species and strains produced β-glucosidase but with different substrate specificities. Moreover, L. theromotolerans and L. fermentati also produced β-xylosidase. H2S production, SO2 and ethanol tolerance was variable between species and strains, with the L. lanzarotensis and L. fermentati displaying considerably high H2S production while L. thermotolerans and L. fermentati displayed higher ethanol tolerance. Furthermore, L. fermentati showed higher SO2 tolerance and could proliferate at 20 mg/L total SO2. Interestingly, an increase in β-glucosidase activity during fermentation did not result in a significant increase in monoterpene concentrations. However, mixed-fermentations with L. fermentati and L. thermotolerans Concerto enhanced geraniol levels. The data show that this activity was mostly cell-associated and constitutively expressed. Sequential fermentations with the Lachancea spp. and S. cerevisiae resulted in wines with significantly altered chemical compositions compared to that obtained from S. cerevisiae inoculated alone. Wines produced from L. thermotolerans and L. lanzarotensis mixed culture fermentations exhibited similar volatile compound composition. Conversely, L. fermentati produced chemically distinct wines consistently associated with high isobutanol and isobutyric acid, and higher monoterpenes. In particular, linalool and geraniol had potential to make perceivable aroma contribution (OAV ≥ 1).