High throughput evaluation of industrial growth conditions for industrial Saccharomyces yeasts

Yeast and Fermentation Session
Anita Van Landschoot, University College Ghent, Ghent, Belgium
Co-author(s): Sylvie Vandoorne and Dana Vanderputten, University College Ghent, Ghent, Belgium; Gary Prescott, BioTek Instruments Inc., Luzern, Switzerland

ABSTRACT: Saccharomyces strains are industrially important yeasts in the production of many beverages. The ability to obtain the desired product reliably and repeatedly in the same amounts requires careful monitoring of not only the material inputs, but also the growth of the yeast strain during propagation or hydration/revitalization, in the case dried yeast, that is used for the fermentation process. This often requires monitoring of the growth of these strains under various conditions to optimize industrial conditions. The Synergy H1 hybrid multi-mode microplate reader was used to provide temperature control, suspension agitation, and monitor cellular yeast growth using light scattering in 96-well microplates at 600 nm. Measurements were made every 2 min, and data were collected using Gen5 data analysis software. The system was used to explore the optimum conditions for propagation and hydration/revitalization of 13 industrial yeast strains. These Saccharomyces yeasts were used to study the effect of temperature, pH, and density of industrial media (wort or must of white grapes) on yeast growth/biomass production. Lowering the pH of the wort to an industrially acceptable value of 4.8 had almost no effect on yeast growth for the different densities of the wort. Lowering the density of the wort or must to about 10°P extract of malt or grapes always had a positive effect on yeast growth. This proved that such medium contains sufficient nutrients for the industrially necessary yeast growth during propagation or hydration/revitalization. If it is industrially relevant, a higher yeast growth temperature can be used. At 30°C the same final cell number can be obtained in half the time compared to room temperature. The final conclusion is that the Synergy H1 microplate reader is a useful high throughput system to screen for optimal industrial growth/revitalization conditions for industrial yeasts. The system has also been tested for fast screening of yeast fermentation conditions.

Anita Van Landschoot is a professor at University College Ghent and Ghent University and lecturer in brewing technology and industrial microbiology. The research of Anita’s group is related to applications of microbial and enzymatic biotechnology: industrial yeast starter cultures, microbial contaminants, microbial populations, antibacterial activity, industrial fermentation processes, glycobiology, and isolation and characterization of microorganisms and some enzymes. The group has the technology and know-how for extraction and fermentation of biomass to ethanol and for the brewing of most Belgian beer types. Most of the research is done in collaboration with industry. The brewing lab represents the oldest Belgian brewing institute.