9708299 DaSilva The yeast Saccharomyces cerevisae is a very important industrial microorganism, and a key laboratory microorganism for understanding eucaryotic cell processes. The strains employed range from genetically well-characterized haploid or diploid strains to the relatively uncharacterized industrial polyploid strains. The ability to introduce stable foreign genes at optimum copy number is extremely important, and the ability to engineer the metabolism of this yeast has tremendous potential. Straightforward methods to stably insert a series of the same or different genes at precise copy numbers have not been developed, and the regulated insertion of multiple genes into the industrially important polyploid yeast has not been addressed. This project addresses these needs by developing and applying methods for the sequential integration of pathway and product genes in both laboratory and industrial (including polyploid) yeast strains. The knowledge to be obtained is to contribute to the improvement of recombinant yeast expression systems, and may provide insight into integration methods of higher eucaryotic cells. ***
