Industrial Wine Yeast Strains Research Articles

Performance of Industrial Strains of Saccharomyces cerevisae During Wine Fermentation is Affected by Manipulation Strategies Based on Sporulation

Genetic manipulation of industrial wine yeast strains has become an essential tool for both the study of the molecular mechanisms underlaying their physiology and the improvement of their fermentative properties. The construction of null mutants for any gene in these usually diploid strains, by using a procedure based on sporulation of a heterozygote lacking one copy of the gene of interest, has been tested as an alternative to the tedious work of sequential disruption of the complete set of copies. Our results indicate that most of the homozygotes resulting from sporulation of wine yeast strains are defective in glucose consumption under microvinification conditions in synthetic must and produce stuck fermentations. These kinds of defects are observed even for strains derived from sporulation of wild type. Alteration of genomic features of wine strains by sporulation is responsible for these defects.

Evaluation of the use of phase-specific gene promoters for the expression of enological enzymes in an industrial wine yeast strain

Genes as POT1, HSP104 and SSA3, which are late expressed in laboratory culture conditions are expressed only during the first few days in microvinifications in wine yeast cells. This effect is probably due to the different growth conditions and leads to useless levels of enzyme activity for a reporter gene. However the ACT1 promoter, which is constitutively expressed in laboratory conditions, produces sufficient amounts of enzyme activity in late fermentation phases.

Construction of a recombinant wine yeast strain expressing a fungal pectate lyase gene

A gene fusion between the Saccharomyces cerevisiae actin gene promoter and the cDNA of the Fusarium solani f. sp. pisi pelA gene has been constructed. This expression cassette has been introduced into the industrial wine yeast strain T 73. The resulting recombinant strain is able to secrete active PELA enzyme into the culture medium. In preliminary microvinification experiments the wine produced by this pectinolytic strain is indistinguishable from wine produced using the non-transformed strain on the basis of the chemical analyses. Large scale fermentations need to be carried out in order to assess the effects on filtrability.

Construction of a recombinant wine yeast strain expressing a fungal pectate lyase gene

A gene fusion between the Saccharomyces cerevisiae actin gene promoter and the cDNA of the Fusarium solani f. sp. pisi pelA gene has been constructed. This expression cassette has been introduced into the industrial wine yeast strain T73. The resulting recombinant strain is able to secrete active PELA enzyme into the culture medium. In preliminary microvinification experiments the wine produced by this pectinolytic strain is indistinguishable from wine produced using the non-transformed strain on the basis of the chemical analyses. Large scale fermentations need to be carried out in order to assess the effects on filtrability.

Construction of a recombinant wine yeast strain expressing beta-(1,4)-endoglucanase and its use in microvinification processes

A genetic transformation system for an industrial wine yeast strain is presented here. The system is based on the acquisition of cycloheximide resistance and is a direct adaptation of a previously published procedure for brewing yeasts (L. Del Pozo, D. Abarca, M. G. Claros, and A. Jiménez, Curr. Genet. 19:353-358, 1991). Transformants arose at an optimal frequency of 0.5 transformant per microgram of DNA, are stable in the absence of selective pressure, and produce wine in the same way as the untransformed industrial strain. By using this transformation protocol, a filamentous fungal beta-(1,4)-endoglucanase gene has been expressed in an industrial wine yeast under the control of the yeast actin gene promoter. Endoglucanolytic wine yeast secretes the fungal enzyme to the must, producing a wine with an increased fruity aroma.