Handbook of Enology: Volume 1. Pascal Ribéreau-Gayon

Handbook of Enology: Volume 1 - Pascal Ribéreau-Gayon


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molecular weight marker; T, negative control.

      Saccharomyces uvarum strains cannot be distinguished by this technique because their genome contains only a few Ty elements.

      1.9.6 PCR with Microsatellites

Schematic illustration of electrophoresis in agarose gel (1.8%) of amplified fragments illustrating examples of yeast implantation tests. Schematic illustration of determination of the detection threshold of a contaminating strain.

      Microsatellite analysis has also been used to identify the strains of S. uvarum (Masneuf‐Pomarède et al., 2007, 2016) and of S. kudriavzevii (Erny et al., 2012) used in winemaking. As the S. uvarum, S. kudriavzevii, and S. cerevisiae microsatellites have different amplification primers, this method provides an additional means of distinguishing between these species and their hybrids.

      The development of new‐generation sequencing methods for yeast genomes has made sequences available for non‐Saccharomyces species. A typing method of yeast strains by microsatellite marker analysis is now offered for B. bruxellensis, T. delbrueckii, H. uvarum, and Starmerella bacillaris (Albertin et al., 2014a,b, 2016; Masneuf‐Pomarede et al., 2015, 2016). When applied to the study of a great number of yeast isolates, these methods help to better describe the genetic diversity and the population structure of winemaking yeasts. Factors influencing this structure as well as their life cycle and reproduction mode have also been described. From an applied point of view, this molecular typing method is a useful tool in winemaking yeast strain identification, ecological surveys, and quality control of industrial production batches.

      1.9.7 Genome Sequencing

      With the development of new‐generation sequencing methods, new approaches to yeast characterization have been suggested. The multilocus sequence typing (MLST) method is a standardized approach to full or partial sequence analysis of certain gene expressions in yeast. These genes are characterized by a slow accumulation of mutations, which help differentiate between individuals, as well as deduce phylogenetic relationships between strains. Applied to S. cerevisiae, the results obtained do not indicate a superior ability to discriminate among yeast strains when compared with analysis by repetitive‐element PCR or microsatellite marker polymorphism (Ayoub et al., 2006). However, studies have revealed the specific population structure of wine yeasts, confirming the domestication of these yeasts (Fay and Benavides, 2005). Other approaches consist in establishing sequences of regions located between randomly selected restriction sites in the genome (restriction site‐associated DNA sequencing or RAD‐seq). Many positions of variation of a base, or single nucleotide polymorphism (SNP), can thus be used for phylogenetic analyses. The RAD‐seq method has established the diversity and genetic structure of S. cerevisiae strains from a variety of ecological niches (Cromie et al., 2013; Hyma and Fay, 2013).

      1.10.1 Succession of Grape and Wine Yeast Species

      A large amount of research was focused on the description and ecology of wine yeasts. It concerned the distribution and succession of species found on the grape and then in wine during fermentation and conservation (Ribéreau‐Gayon et al., 1975; Lafon‐Lafourcade, 1983).

      The ecological study of grape and wine yeast species represents a considerable amount of research. De Rossi began his


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