Collaboration with Bordeaux researchers to explore genotypic and phenotypic diversity of Lachancea thermotolerans - a promising non-Saccharomyces for winemaking

Abstract

This travel grant provided University of Adelaide PhD student, Ana Hranilovic, support during a research stay at the ISVV, University of Bordeaux working on non-Saccharomyces yeasts. Non-Saccharomyces yeasts naturally occur in the wine-related environment, but are far less studied compared to the 'conventional' wine yeast, Saccharomyces cerevisiae. One such yeast is Lachancea thermotolerans, a species of remarkable oenological potential. Its association with S. cerevisiae can lead to wine acidification, lower ethanol content and an increased aromatic complexity. The study undertaken examined the genetic and phenotypic diversity of a large set of L. thermotolerans isolates sourced from a variety of habitats worldwide, revealing a grouping based on the geographic localisation and the isolation substrate.

Summary

The focus of this travel grant was to facilitate a study at the ISVV, University of Bordeaux on Lachancea thermotolerans, a species with several valuable oenological traits. These include wine acidification, due to lactic acid production, and the potential to decrease final wine ethanol concentration in co-fermentation with S. cerevisiae. The targeted use of L. thermotolerans to (partially) conduct the fermentation can therefore be used to obtain wines of an increased quality, stability and marketability, whilst reducing inputs related to grape processing (e.g. tartaric acid, dealcoholisation). This is of particular interest in the context of viticultural and oenological practices, underlined by observed and/or projected climate warming, leading to higher pH levels and excess sugar accumulation at harvest. A pre-requirement for the wider implementation of L. thermotolerans in industry is, however, a thorough characterisation of the species to gain an understanding of its ecophysiology and evolution.

To accomplish this, a large set of Lachancea isolates (~200) were sourced from different habitats (grapes, forest material, insects, etc.), covering a large geographic span. 14 microsatellite markers were developed and optimised to conduct a population genetics study aimed at assessing the proximity and the divergence of isolates.