Characterisation of Saccharomyces cerevisiae and Saccharomyces jurei hybrids for oenological applications

Abstract

The Saccharomyces genus present as a genetically diverse set of microorganisms capable of tolerating a range of environmental stressors, demonstrating high fermentation capacity and producing interesting flavour compounds. Such diversity can be exploited in a single organism by producing interspecies hybrids, overcoming the limitations of a single species. Here, as proof of principle, we exploited a library of F12 interspecies diploid hybrids between Saccharomyces cerevisiae and Saccharomyces jurei (Sc/Sj), to identify new strains harbouring traits of oenological relevance, such as ethanol and glycerol production, superior tolerance to acetic acid, limited production of H2S, and optimal growth on fructose. Moreover, we calculated robustness across strains tested on solid media comparing the trade-off between performance on a single conditions and overall robustness. Progeny from a range of robustness values with favourable H2S production profiles were isolated for further analysis via micro and small-scale fermentations. Micro-scale fermentations in synthetic grape must containing individual wine-associated stressors were performed, and the robustness of the selected strains was confirmed. The wine characteristics of the hybrids were tested in small-scale fermentations in synthetic grape media. We found that both ethanol and glycerol production across our selected progeny matched or exceeding that from the commercial wine strain, and most hybrids produced less acetic acid and more fatty-acids, including higher quantities of associated esters. Overall, we were able to identify suitable Sc/Sj hybrids with interesting aroma profiles to develop further for wine fermentation.