Biotechnological evaluation of temperature induced gene expression and metabolome modulation of self-cloning Saccharomyces yeast

• Applicants: Professor Dr.-Ing. Thomas Becker; Professor Dr. Thomas Hofmann
• Subject Area: Biological Process Engineering ; Plant Cultivation, Plant Nutrition, Agricultural Technology
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 269148392

The beverage processing Saccharomyces yeast underlies several stressors, such as temperature, osmotic pressure, oxygen and nutrient starvation. All these factors regulate the induction of genes involved in stress response and its related metabolism. Yeast gene expression can also be induced directly due to different specific process parameters acting as stress inducers. In this project native promoters of stress inducible genes of Saccharomyces pastorianus var. carlsbergensis strain TUM 34/70 and Saccharomyces cerevisiae strain TUM 68 will be evaluated by different heat and cold shocks. The resulting induction capacity of the promoters will be analyzed by the expression level of the green fluorescence protein (eGFP) and its fluorescence detection. The inducibility of the expression intensity as well as the bioprocessing compatibility with respect to the temperature, substrate availability and physiological conditions of the yeast during different stress conditions will be evaluated based on industrial realizable process parameters in order to generate the rational use of process optimized yeast. Selected genes (ATF1 and GPD1) which have product improving properties with respect to the biosynthesis of volatile esters and relevant metabolites will be controlled by the evaluated promoters to create self-cloning yeast strains. The temperature induced activation of these expression systems contribute to the efficiency of yeast fermented beverages in order to optimize the flavor profile. Furthermore, quantitative and qualitative determination of key-metabolites of the yeast metabolism will be analyzed by differential off-line-LC/NMR-Analytic complimented by established HILIC-MS/MS-methods. In addition the enzyme activity and the stability of the proteins (Atf1p and Gpd1p), underlying different stressors, will be analyzed especially at the end of the fermentation process. Furthermore, the metabolic and physiological conditions of the yeast as well as the growth kinetics of the self-cloning strains under different stress situations will be studied.

• DFG Programme: Research Grants