A physical method for separating Saccharomyces cerevisiae cells according to their ploidy.

A centrifugation technique, using genetically marked Saccharomyces cerevisiae strains, has been developed to separate Saccharomyces cerevisiae cells of different ploidy levels from exponential phase cultures. The method involves the conversion of yeast cells to protoplasts, the separation of the protoplasts on an osmotically stabilized Nycodenz gradient, and their regeneration. This type of selection may be of importance where selectable markers are not available.