CONSTRUCTION OF A RECOMBINANT WINE YEAST-STRAIN EXPRESSING BETA-(1,4)-ENDOGLUCANASE AND ITS USE IN MICROVINIFICATION PROCESSES

A genetic transformation system for an industrial wine yeast strain is presented here. The system is based on the acquisition of cycloheximi de resistance and is a direct adaptation of a previously published pro cedure for brewing yeasts (L. Del Pozo, D. Abarca, M. G. Claros, and A . Jimenez, Curr. Genet. 19:353-358, 1991). Transformants arose at an o ptimal frequency of 0.5 transformant per mug of DNA, are stable in the absence of selective pressure, and produce wine in the same way as th e untransformed industrial strain. By using this transformation protoc ol, a filamentous fungal beta-(1,4)-endoglucanase gene has been expres sed in an industrial wine yeast under the control of the yeast actin g ene promoter. Endoglucanolytic wine yeast secretes the fungal enzyme t o the must, producing a wine with an increased fruity aroma.