Oenological traits of Lachancea thermotolerans show signs of domestication and allopatric differentiation

Ana Hranilovic,Joanna M Gambetta,Paul R Grbin,Marina Bely,Vladimir Jiranek,Leigh Schmidtke,Isabelle Masneuf-Pomarede,Warren Albertin,Paul K Boss

doi:10.1038/s41598-018-33105-7

Abstract

The yeast Lachancea thermotolerans (previously Kluyveromyces thermotolerans) is a species of large, yet underexplored, oenological potential. This study delivers comprehensive oenological phenomes of 94 L. thermotolerans strains obtained from diverse ecological niches worldwide, classified in nine genetic groups based on their pre-determined microsatellite genotypes. The strains and the genetic groups were compared for their alcoholic fermentation performance, production of primary and secondary metabolites and pH modulation in Chardonnay grape juice fermentations. The common oenological features of L. thermotolerans strains were their glucophilic character, relatively extensive fermentation ability, low production of acetic acid and the formation of lactic acid, which significantly affected the pH of the wines. An untargeted analysis of volatile compounds, used for the first time in a population-scale phenotyping of a non-Saccharomyces yeast, revealed that 58 out of 90 volatiles were affected at an L. thermotolerans strain level. Besides the remarkable extent of intra-specific diversity, our results confirmed the distinct phenotypic performance of L. thermotolerans genetic groups. Together, these observations provide further support for the occurrence of domestication events and allopatric differentiation in L. thermotolerans population.

Highlights

In oenological environments, L. thermotolerans is a relatively robust fermenter, depending on the strain and physiochemical conditions, capable of achieving up to 13.6% (v/v) ethanol[11]
The strains and the genetic groups were compared for the microbial growth and sugar consumption kinetics, final production of primary and secondary metabolites and pH modulation in 25 mL Chardonnay grape juice fermentations (Supplementary Fig. S2)
The analysis revealed that the most explanatory variable for pH was lactic acid, accounting for 73% of variation (Fig. 5)

Summary

Introduction

L. thermotolerans is a relatively robust fermenter, depending on the strain and physiochemical conditions, capable of achieving up to 13.6% (v/v) ethanol[11]. The resultant acidification is considered to positively affect wine microbial stability and organoleptic balance, while alleviating the need for external inputs (e.g. tartaric acid) commonly used to acidify grapes from warmer climates/vintages[7,10,18]. Another common characteristic of such grapes is excessive sugar accumulation, leading to undesirably high ethanol concentrations in wines[19].

Methods

Results

Conclusion