Genetic improvement  of  thermo-tolerance in wineSaccharomyces cerevisiae  strains by a backcross approach

Abstract

During red wine fermentation, high temperatures may cause stuck fermentation by affecting the physiology of fermenting yeast. This deleterious effect is the result of the complex interaction of temperature with other physicochemical parameters of grape juice, such as sugar and lipid content. The genetic background of fermenting yeast also interacts with this complex matrix and some strains are more resistant to high temperatures than others. Here, the temperature tolerance of nine commercial starters was evaluated, demonstrating that, at high sugar concentrations, half of them are sensitive to temperature. Using a classical backcross approach, one thermo-sensitive commercial starter was genetically improved by introducing quantitative trait loci conferring resistance to temperature. With this breeding program it is possible to obtain a thermo-resistant strain sharing most of its genome with the initial commercial starter. The parental and improved strains were compared for population growth and fermentation ability in various conditions. Despite their common genetic background, these two strains showed slight physiological differences in response to environmental changes that enable identification of the key physiological parameters influencing stuck fermentation.

Population Size Drives Industrial Saccharomyces cerevisiae Alcoholic Fermentation and Is under Genetic Control

“…The correlation found between K and V max suggests that increasing K would also increase fermentative ability. Accordingly, previous data showed that a higher carrying capacity was associated with a higher CO 2 production rate in nearly isogenic S. cerevisiae strains (38), and Varela et al (66) showed that adding biomass reduced the time to achieve sugar consumption in slow fermentations. Using K as a selection criterion for AF would therefore increase the rate of fermentation.…”

“…Here, we proposed a new strategy to preselect S. cerevisiae strains with good fermentative potential, based on their carrying capacity: measuring K can be achieved using a particle counter or a flow cytometer for numerous strains in a short time, allowing the evaluation of hundreds of poorly studied yeast strains available in collection centers. Strains displaying high carrying capacities could then enter traditional breeding programs involving crosses with well-characterized industrial strains, for example (38).…”

“…The use of pure yeast culture to initiate alcoholic fermentation progressively came to dominate worldwide practices, and the utilization of starter strains adapted to each food process is now the rule rather than the exception in brewing, wine making, and baking. Thus, several efforts have been undertaken to improve yeast strains used in the food and beverage industry, using various approaches, such as phenotypic selection of natural isolates (22), mutagenesis (13), clone and meiospore selection (13,36,50), breeding programs assisted by technological tests (13,37,38,55) or quantitative trait locus (QTL) introgression (32,37,39), and genetic engineering (17,68). Yeast improvement aimed at enhancing the efficiency of the fermentation process as well as the quality of the products, implying specific biotechnological targets regarding the nature of the final products: freezing tolerance, flocculation, aromatic contribution, and ethanol tolerance, as exhaustively described in the literature (18,34,47).…”

Enhancement of Ethanol Fermentation in Saccharomyces cerevisiae Sake Yeast by Disrupting Mitophagy Function

“…S2 in the supplemental material), suggesting that this strain would be a practical strain for industrial application. Enhancing fermentation output is the subject of intensive research on brewery yeasts (42,43). An obvious benefit of these efforts includes reduced production costs, for example, of bioethanol and alcoholic beverages.…”

Análisis del metabolismo nitrogenado durante la fermentación alcohólica en levaduras vínicas (Nitrogen metaolism in wine yeast during alcoholic fermentation: effect on growth, fermentation activity and aroma production)

“…Although tremendous progress has been made in genetic engineering to improve wine yeasts, genetically modified organisms (GMO) are still controversial. The use of molecular breeding techniques for unconsidered GMOs, such as intra-and inter-specific hybridization (Pérez-Través et al, 2012) or the classical backcross approach (Marullo et al, 2009), can prove very useful for introducing quantitative trait loci into a commercial strain background or for curing a genetic mutation.…”