Evolution of a Yeast With Industrial Background Under Winemaking Conditions Leads to Diploidization and Chromosomal Copy Number Variation.

Ana Mangado,Ramon Gonzalez,Pilar Morales,Jordi Tronchoni

doi:10.3389/fmicb.2018.01816

Abstract

Industrial wine yeast strains show genome particularities, with strains showing polyploid genomes or chromosome copy number variations, being easier to identify. Although these genomic structures have classically been considered transitory steps in the genomic adaptation to new environmental conditions, they may be more stable than thought. These yeasts are highly specialized strains able to cope with the different stresses associated with the fermentation process, from the high osmolarity to the final ethanol content. In this work, we use adaptive laboratory evolution, focusing on the initial steps of the fermentation process, where growth rate is maximum, to provide new insights into the role of the different genomic and chromosomic rearrangements that occur during adaptation to wine conditions, and providing an understanding of the chronology of the different evolutionary steps.

Highlights

Industrial yeast strains are an essential element in the production of various goods for human use, from the traditional food related, bread, beer, and wine to the more recently and technological, bioethanol, heterologous proteins, and low-molecular-weight compounds (Pretorius, 2000; Mattanovich et al, 2014; de Vries et al, 2017)
At genomic level, domesticated yeast strains show higher frequencies of polyploid genomes compared to strains found in nature, this is even more common in industrial hybrid strains, while at chromosomal level it is easy to find variations in the number of copies of chromosomes (Sipiczki, 2011; Steensels et al, 2014; de Vries et al, 2017; Guillamón and Barrio, 2017)
Diploidization and aneuploidies have been described as evolutionary phenomena that allow adaptation to a new niche where growth conditions are different or particular

Summary

Introduction

Industrial yeast strains are an essential element in the production of various goods for human use, from the traditional food related, bread, beer, and wine to the more recently and technological, bioethanol, heterologous proteins, and low-molecular-weight compounds (Pretorius, 2000; Mattanovich et al, 2014; de Vries et al, 2017). The traditional yeast strains, and those that have emerged more recently to enable new industrial applications, have a number of genomic characteristics in common that distinguish them from wild strains. Being particularity beneficial under unstable circumstances (Comai, 2005; Sheltzer and Amon, 2011). These types of adaptations have been considered generally transitory with the main role being to generate the appropriate conditions to allow gene speciation, by increasing the number of copies of genes or allowing the presence of SNPs in heterozygosis.

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