Genetic engineering of wine yeast strains requires the identification
of gene promoters specifically activated under wine processing conditi
ons. In this study, transcriptional activation of specific genes was f
ollowed during the time course of wine fermentation by quantifying mRN
A levels in a haploid wine strain of Saccharomyces cerevisiae grown on
synthetic or natural winery musts. Northern analyses were performed u
sing radioactive probes from 19 genes previously described as being ex
pressed under laboratory growth conditions or on molasses in S. cerevi
siae during the stationary phase and/or under nitrogen starvation. Nin
e genes, including members of the HSP family, showed a transition-phas
e induction profile. For three of them, mRNA transcripts could be dete
cted until the end of the fermentation. Expression of one of these gen
es, HSP30, was further studied using a HSP30::lacZ fusion on both mult
icopy and monocopy expression vectors. The production of beta-galactos
idase by recombinant cells was measured during cell growth and ferment
ation on synthetic and natural winery musts. We showed that the HSP30
promoter can induce high gene expression during late stationary phase
and remains active until the end of the wine fermentation process. Sim
ilar expression profiles were obtained on five natural winery musts. (
C) 1997 by John Wiley & Sons, Ltd.