Find in Library

Lactic acid production is an important feature of the yeast <i>Lachancea thermotolerans</i> that has gained increasing interest in winemaking. In particular, in light of climate change, the biological acidification and ethanol reduction by the use of selected yeast strains may counteract the effect of global warming in wines. Here, the enological potential of a high lactate-producing <i>L. thermotolerans</i> strain (P-HO1) in mixed fermentations with <i>S. cerevisiae</i> was examined. Among the different inoculation schemes evaluated, the most successful implantation of <i>L. thermotolerans</i> was accomplished by sequential inoculation of <i>S. cerevisiae</i>, i.e., at 1% vol. ethanol. P-HO1produced the highest levels of lactic acid ever recorded in mixed fermentations (10.4 g/L), increasing thereby the acidity and reducing ethanol by 1.6% vol. <i>L. thermotolerans</i> was also associated with increases in ethyl isobutyrate (strawberry aroma), free SO₂, organoleptically perceived citric nuances and aftertaste. To start uncovering the molecular mechanisms of lactate biosynthesis in <i>L. thermotolerans</i>, the relative expressions of the three lactate dehydrogenase (<i>LDH</i>) paralogous genes, which encode the key enzyme for lactate biosynthesis, along with the alcohol dehydrogenase paralogs (<i>ADH</i>s) were determined. Present results point to the possible implication of <i>LDH2</i>, but not of other <i>LDH</i> or <i>ADH</i> genes, in the high production of lactic acid in certain strains at the expense of ethanol. Taken together, the important enological features of P-HO1 highlighted here, and potentially of other <i>L. thermotolerans</i> strains, indicate its great importance in modern winemaking, particularly in the light of the upcoming climate change and its consequences in the grape/wine system.