Michael Sobe,* Juergen Froehlich, Hannes Weninger, and Brett Roden 
*Erbsloeh Geisenheim AG, Erbsloestrasse 1, Geisenheim 65366, Germany (michael.sobe@erbsloeh.com)

As a result of climate change, rising sugar content in grape must and the concomitant increase in alcohol levels in wine are some of the main challenges currently affecting the winemaking industry. Among several solutions now under study, specialized wine yeasts isolated under different selective pressures hold promise for ameliorating this problem. Processes to produce such yeasts are comprised of intentional genetic modification based on selective cultivation without application of GMO-techniques. This objective was achieved by combining different mutagenesis techniques: the first and second mutagens differed and were chosen from the following: nucleotide-alkylating agent, nucleotide-deamination agent, and UV radiation. A first selection step was performed between the first and second mutagenesis steps, and a second selection step was performed after the second mutagenesis step, in which the mutants resulting from the preceding mutagenesis step were exposed to hypertonic medium and alcohol dehydrogenase inhibitor selection factors. Finally, these strains were subjected to RNA microarray tests which showed that genes of the HOG (High Osmolarity Glycerol) pathway were mainly affected by the mutagenesis experiments.

Funding Support: Erbsloeh Geisenheim AG