Section: New Results
Analysis of oenological genomes
Participants : David James Sherman, Pascal Durrens [ correspondant ] , Elisabeth Bon.
Two activities contributed to improved understanding of the relation between genome variation and efficiency of cell factory microorganisms used in wine making. The first, led by Pascal Durrens, is analysis and mapping of the genomes variations involved in quantitative traits. In collaboration with the ISVV, we detect and map single nucleotide polymorphism (SNP) associated with fermentation parameters during wine fermentation by oenological yeasts. The results will be exploited both in yeast strain improvement (selection of the relevant gene variants) and in modelisation of the fermenting cell (indication of the key metabolic steps).
The second is led by Elisabeth Bon. Through her association with Magnome , the team has acquired a new expertise on prokaryotic models, and notably on the non-pathogenic food production bacterium, Oenococcus oeni. This species is part of the natural microflora of wine and related environments, and is the main agent of the malolactic fermentation (MLF), a step of wine making that generally follows alcoholic fermentation (AF) and contributes to wine deacidification, improvement of sensorial properties and microbial stability. The start, duration and achievement of MLF are unpredictable since they depend both on the wine characteristics and on the properties of the O. oeni strains. Elisabeth is in charge of sequencing effort coordination, explorative and comparative genome data analysis, and comparative genomics. In comparative genomics, we investigated gene repertoire and genomic organization conservation through intra- and inter-species genomic comparisons, which clearly show that the O. oeni genome is highly plastic and fast-evolving. Preliminary results reveal that the optimal adaptation to wine of a strain mostly depends on the presence of key adaptative loops and polymorphic genes. They also point up the role of horizontal gene transfer and mobile genetic elements in O. oeni genome plasticity, and give the first clues of the genetic origin of its oenological aptitudes.