PRESENCE OF STA GENE-SEQUENCES IN BREWERS-YEAST GENOME

STA genes are responsible for producing extracellular glucoamylase enz ymes in Saccharomyces cerevisiae var. diastaticus. These genes exist i n three forms, which are located on three different chromosomes. The n ucleotide sequences of the STA genes are highly homologous. A sporulat ion-specific glucoamylase gene called SGAl exists in every Saccharomyc es cervisiae strain, this also having a partly homologous DNA sequence with the STA genes. In this study S. cerevisiae var. diastaticus and brewer's yeast strains were characterized by pulsed-field gel electrop horesis. In many cases chromosome length polymorphism (CLP) was found. The chromosomes were hybridized with a DNA probe which was homologous with STA genes and the SGAl gene. Presence of the SGAl gene was detec ted in each strain used. Four brewing yeasts were found to have homolo gous sequences with the STA3 gene on chromosome XIV despite the fact t hat theses strains were not able to produce extracellular glucoamylase enzyme.