Effects of changes in the mitochondrial genome on the performance of baking yeasts.

Modifications to the mitochondria in baking yeasts affect their performance in dough-raising tests significantly. Conversion of a respiratory-competent baking strain, sensitive to glucose repression, to the petite mutant, yielded a strain which was released from this effect, as shown by the increased development of the cytochrome c peak in the cytochrome spectrum, and which showed a comparably improved dough-raising performance, approaching the levels found for a respiratory-competent strain which was fully derepressed. Replacement of the mitochondria of one strain by those from another, in some cases, improved the performance of the recipient strain, especially if the latter was sensitive to glucose repression. In addition, reduction of glucose repression in single-spore clones derived from the composite strains, as determined by the increased size of the cytochrome c peak, usually segregated 2:2 both for this character and for improved dough-raising capability as well.