Construction of brewer's yeasts secreting fungal endo-ß-glucanase

Barley β-glucans present in wort reduce beer filtrability and cause hazes and precipitates in the finished beer. The endo-β-1,4-glucanase enzyme, EGI, found in the filamentous fungus Trichoderma reesei, is capable of efficiently hydrolyzing these β-glucans. The cDNA copy of the eg11 gene, which codes for the EGI enzyme, was coupled to yeast regulatory sequences and transferred to a brewer's yeast using the yeast copper chelatin gene CUP1 as a selection marker in the transformation. The eg11 gene was transferred to the yeast both on a multicopy plasmid and on an integrating plasmid. In both cases, highly glycosylated, active EGI enzyme was secreted into the medium. Barley β-glucans present in wort were efficiently hydrolyzed by the recombinant brewer's yeast.