Improvement of protoplast regeneration by growing yeast cells hypertonically.

The high osmotic pressure provided for in vitro transformation processes to support naked protoplasts of Saccharomyces cerevisiae was found to hurt regeneration of the protoplasts to walled cells. Preadaptation of the cells by growth under the same hypertonic conditions as those used for transformation doubled the rate of protoplast regeneration and in turn resulted in a higher yield of transformants.