Survey of molecular methods for the typing of wine yeast strains

A survey of the genetic polymorphisms produced by distinct methods was performed in 23 commercial winery yeast strains. The microsatellite typing, using 6 different loci, an optimized interdelta sequence analysis and RFLP of mitochondrial DNA generated by the enzyme Hinf I had the same discriminatory power: among the 23 commercial yeast strains, 21 distinct patterns were obtained. Karyotype analysis originated 22 patterns, thereby allowing the discrimination of one of the three strains that were not distinguished by the other methods. Due to the equivalence of the results obtained in this survey, any of the methods can be applied at the industrial scale.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/BIO/38106/2001 (Eixo 2, Medida 2.3, QCAIII - FEDER).Instituto de Cooperação Científica e Tecnológica Internacional (ICCTI) - grant nº 657 C2.Comunidade Europeia (UE) - contract number QLK4-CT-2001-51873

Genetic characterization of commercial saccharomyces cerevisiae isolates recovered from vineyard environments

One hundred isolates of the commercial S. cerevisiae strain Zymaflore VL1 were recovered from spontaneous fermentations carried out with grapes collected from vineyards located close to wineries in the Vinho Verde Wine Region (Portugal). Isolates were differentiated based on their mitochondrial DNA restriction patterns and the evaluation of genetic polymorphisms was carried out by microsatellite analysis, interdelta sequence typing and pulse field gel electrophoresis. Genetic patterns were compared to the ones obtained for 30 isolates of the original commercialized Zymaflore VL1 strain. Among the 100 recovered isolates we found a high percentage of chromosomal size variations, most evident for the smaller chromosomes III and VI. Complete loss of heterozygosity was observed for two isolates that also lost chromosomal heteromorphism; their growth and fermentative capacity in a synthetic must medium was also affected. Considerably higher number of variant patterns for interdelta sequence amplifications was obtained for grape-derived strains compared to the original VL1 isolates. Our data show that the permanence of strain VL1 in natural grapevine environments induced genetic changes that can be detected different fingerprinting methods. The observed genetic changes may reflect adaptive mechanisms to changed environmental conditions that yeast cells encounter during their permanence in nature.This study was funded by the programs POCI 2010 (FEDER/FCT, POCI/AGR/56102/2004) and AGRO (ENOSAFE, No. 762), Portugal

Whole genome analysis of a wine yeast strain

Saccharomyces cerevisiae strains frequently exhibit rather specific phenotypic features needed for adaptation to a special environment. Wine yeast strains are able to ferment musts, for example, while other industrial or laboratory strains fail to do so. The genetic differences that characterize wine yeast strains are poorly understood, however. As a first search of genetic differences between wine and laboratory strains, we performed DNA-array analyses on the typical wine yeast strain T73 and the standard laboratory background in S288c. Our analysis shows that even under normal conditions, logarithmic growth in YPD medium, the two strains have expression patterns that differ significantly in more than 40 genes. Subsequent studies indicated that these differences correlate with small changes in promoter regions or variations in gene copy number. Blotting copy numbers vs. transcript levels produced patterns, which were specific for the individual strains and could be used for a characterization of unknown samples. Copyright © 2001 John Wiley & Sons, Ltd

Phenotypic and genotypic diversity of wine yeasts used for acidic musts

The aim of this study was to examine the physiological and genetic stability of the industrial wine yeasts Saccharomyces cerevisiae and Saccharomyces bayanus var. uvarum under acidic stress during fermentation. The yeasts were sub-cultured in aerobic or fermentative conditions in media with or without l-malic acid. Changes in the biochemical profiles, karyotypes, and mitochondrial DNA profiles were assessed after minimum 50 generations. All yeast segregates showed a tendency to increase the range of compounds used as sole carbon sources. The wild strains and their segregates were aneuploidal or diploidal. One of the four strains of S. cerevisiae did not reveal any changes in the electrophoretic profiles of chromosomal and mitochondrial DNA, irrespective of culture conditions. The extent of genomic changes in the other yeasts was strain-dependent. In the karyotypes of the segregates, the loss of up to 2 and the appearance up to 3 bands was noted. The changes in their mtDNA patterns were much broader, reaching 5 missing and 10 additional bands. The only exception was S. bayanus var. uvarum Y.00779, characterized by significantly greater genome plasticity only under fermentative stress. Changes in karyotypes and mtDNA profiles prove that fermentative stress is the main driving force of the adaptive evolution of the yeasts. l-malic acid does not influence the extent of genomic changes and the resistance of wine yeasts exhibiting increased demalication activity to acidic stress is rather related to their ability to decompose this acid. The phenotypic changes in segregates, which were found even in yeasts that did not reveal deviations in their DNA profiles, show that phenotypic characterization may be misleading in wine yeast identification. Because of yeast gross genomic diversity, karyotyping even though it does not seem to be a good discriminative tool, can be useful in determining the stability of wine yeasts. Restriction analysis of mitochondrial DNA appears to be a more sensitive method allowing for an early detection of genotypic changes in yeasts. Thus, if both of these methods are applied, it is possible to conduct the quick routine assessment of wine yeast stability in pure culture collections depositing industrial strains

Amplification of a Zygosaccharomyces bailii DNA Segment in Wine Yeast Genomes by Extrachromosomal Circular DNA Formation

We recently described the presence of large chromosomal segments resulting from independent horizontal gene transfer (HGT) events in the genome of Saccharomyces cerevisiae strains, mostly of wine origin. We report here evidence for the amplification of one of these segments, a 17 kb DNA segment from Zygosaccharomyces bailii, in the genome of S. cerevisiae strains. The copy number, organization and location of this region differ considerably between strains, indicating that the insertions are independent and that they are post-HGT events. We identified eight different forms in 28 S. cerevisiae strains, mostly of wine origin, with up to four different copies in a single strain. The organization of these forms and the identification of an autonomously replicating sequence functional in S. cerevisiae, strongly suggest that an extrachromosomal circular DNA (eccDNA) molecule serves as an intermediate in the amplification of the Z. bailii region in yeast genomes. We found little or no sequence similarity at the breakpoint regions, suggesting that the insertions may be mediated by nonhomologous recombination. The diversity between these regions in S. cerevisiae represents roughly one third the divergence among the genomes of wine strains, which confirms the recent origin of this event, posterior to the start of wine strain expansion. This is the first report of a circle-based mechanism for the expansion of a DNA segment, mediated by nonhomologous recombination, in natural yeast populations

A Handfoult of Sasseigners : une dette linguistique

In the early twentieth century a number of Irish nationalists considered the revival of the Gaelic language a precondition for any political undertaking. In A Portrait of the Artist as a Young Man Stephen Dedalus declares that he has no intention of adopting Gaelic in order to settle the language debts his ancestors made centuries ago, when they borrowed English from the Saxon invaders. The language issue in Ireland as seen through Stephen's eyes is particularly complex, notably because the mother tongue - English - is perceived as foreign, whereas the foreign language - Gaelic - is perceived as motherly. This manifests itself in the young man's ambivalent feelings towards the two languages as well as in his superiority-and-inferiority complex towards English as it is spoken by the English. This complexity was experienced by James Joyce himself, but as a toriter his opposition to the advocates of the revival of Gaelic was not, like Stephen's, a mere ideological or theatrical denial. That was the reason why he began to settle his ancestors' debts - without ever intending to do it once and for all by giving up English. He did so, from A Portrait to Finnegans Wake, by borrowing more and more words from more languages. Besides, it would be as appropriate to refer to settling the score rather than debts, with English, but also with Gaelic - a never-ending business.Au début du XXe siècle, une partie des nationalistes irlandais faisaient de l'adoption de la langue gaélique un préalable à toute entreprise politique. Dans A Portrait of the Artist as a Young Man Stephen Dedalus déclare qu'il n'a aucunement l'intention d'adopter le gaélique afin de rembourser la dette linguistique contractée il y a des siècles par ses ancêtres irlandais, lorsqu'ils empruntèrent leur langue aux conquérants anglais. La question linguistique irlandaise, vue à travers le personnage de Stephen, est particulièrement complexe, notamment en ce que la langue maternelle - l'anglais - est ressentie comme étrangère, tandis que la langue étrangère - le gaélique - a quelque chose de maternel. Ceci se manifeste dans les sentiments ambivalents du jeune homme vis-à-vis des deux langues, ainsi que par son double complexe d'infériorité et de supériorité vis-à-vis de l'anglais tel qu'il est parlé par les Anglais. Cette complexité fut vécue par Joyce lui-même, mais, en tant qu'écrivain, il n'était pas, au contraire de Stephen, en opposition dénégative - idéologique ou théâtrale - avec les tenants du renouveau du gaélique. C'est pour cette raison qu'il commença le remboursement de la dette ancestrale vis-à-vis de l'anglais, sans toutefois vouloir la rembourser une fois pour toutes en abandonnant cette langue. Il le fit, de A Portrait à Finnegans Wake par des emprunts de plus en plus nombreux à un nombre croissant de langues. D'ailleurs, autant que d'un remboursement, il conviendrait de parler d'un règlement de comptes - interminable lui aussi -, avec l'anglais, certes, mais aussi avec le gaélique.Bidenne Daniel. A Handfoult of Sasseigners : une dette linguistique. In: Études irlandaises, n°26-2, 2001. La langue gaélique en Irlande hier et aujourd'hui, sous la direction de Danielle Jacquin . pp. 67-80