Identification of genes and proteins induced during the lag and early exponential phase of lager brewing yeasts

Aims: The aim of the present study is to identify genes and proteins whose expression is induced in lager brewing yeast during the lag phase and early exponential growth. Methods and Results: Two-dimensional gel electrophoresis was used to identify proteins induced during the lag and early exponential phase of lager brewing yeast in minimal medium. The identified, early-induced proteins were Ade17p, Eno2p, Ilv5gp, Sam1p, Rps21p and Ssa2p. For most of these proteins, the patterns of induction differed from those of the corresponding genes. However, the genes had similar early expression patterns in minimal medium as observed during lager brewing conditions. The expression of previously identified early-induced genes in Saccharomyces cerevisiae grown in minimal medium, ADO1, ALD6, ASC1, ERG4, GPP1, RPL25, SSB1 and YKL056C, was also early induced in lager yeast under brewing conditions. Conclusions: The results indicate that the above-mentioned genes in general are induced during the lag phase and early exponential growth in Saccharomyces yeasts. The processes in which these genes take part are likely to play an important role during growth initiation. Significance and Impact of the Study: Increased knowledge regarding the early growth phase of lager brewing yeast was obtained. Further, the universality of the identified expression patterns suggests new methodologies for optimization and control of growth initiation during brewing fermentations.