Bayanus Strains Research Articles

Influence of yeast strain on the composition of wines for the production of brandy

FifteenSaccharomyces strains used in the production of Trebbiano wine for brandy were examined. The chemical analysis of the wine showed significant differences depending on the yeast strain used. In particular,Sacch. bayanus strains produced many compounds desirable for flavour effects (i.e. 2‐phenethyl alcohol) and few undesirable compounds, such as acetic acid and sulphur anhydride.

Sequence analysis of the right end of chromosome XV in Saccharomyces cerevisiae: An insight into the structural and functional significance of sub‐telomeric repeat sequences

Approximately 3.9 kb of DNA, centromere proximal to the previously sequenced Y' element at the right end of chromosome XV in Saccharomyces cerevisiae strain YP1, has been sequenced. A number of the known sub-telomeric repeat sequences were identified, including Y', core X and STRs A, B. C and D. Several of these repeat elements contain potentially functional sequences. In addition, two other members of repeated gene families were identified. The first of these shows 61% and 60% DNA sequence identity to Enolases 1 and 2 respectively. The Enolase-like sequence appears to be species specific, with three copies being found in all strains of S. cerevisiae studied. The location of the three copies is the same for all strains. The second repeated sequence has homology with known open reading frames on chromosomes III, V and XI. There are five or six copies of this sequence in all S. cerevisiae and S. paradoxus strains studied and three in S. bayanus strains. The analysis of this region and comparison to sub-telomeric regions on other chromosomes gives some indication as to the potential functional and structural significance of sub-telomeric repeat sequences. In addition, these findings are consistent with the idea that sub-telomeric regions may be targets for unusual recombination events.

MEL gene polymorphism in the genus Saccharomyces.

In Saccharomyces spp. the ability to use melibiose depends on the presence of a MEL gene encoding alpha-galactosidase. We used two cloned MEL genes as probes to characterize the physical structure and chromosomal location of the MEL genes in several industrial and natural Mel+ strains of Saccharomyces cerevisiae, Saccharomyces pastorianus, and Saccharomyces bayanus. Electrokaryotyping showed that all of the S. pastorianus strains and most of the S. bayanus strains studied had one MEL locus. The MEL gene in S. bayanus strains was similar but not identical to the S. pastorianus MEL gene. Mel+ S. cerevisiae strains had one to seven loci containing MEL sequences. The MEL genes of these strains could be divided into two categories on the basis of hybridization to MEL1, one group exhibiting strong hybridization to MEL1 and the other group exhibiting weak hybridization to MEL1. In S. pastorianus and S. bayanus strains, the MEL gene was expressed as a single 1.5-kb transcript, and the expression was galactose inducible. In some S. cerevisiae strains, the MEL genes were expressed even without induction at fairly high levels. Expression was usually further induced by galactose. In two strains, CBS 5378 and CBS 4903, expression of the MEL genes was at the same level without induction as it was in most other strains with induction. In all S. cerevisiae strains, irrespective of the number of MEL genes, mRNA of only one size (1.6 kb) was observed.

Three newly delimited species of Saccharomyces sensu stricto.

Deoxyribonucleic acid reassociation studies of 24 different wine and beer-associated strains of Saccharomyces confirmed the presence of three separate species. S. cerevisiae and S. bayanus strains had only 22% of their genomes in common. S. pastorianus, with intermediate hybridization values between S. cerevisiae and S. bayanus (52 and 72%, respectively) could possibly be a natural hybrid of the two species. S. pastorianus replaces S. carlsbergensis with which it is homologous for 93% of its genome, since the former species was described first by Hansen in 1904. These data do not agree with the results of traditional physiological tests.