Breeding of a Sake Yeast Which Produces a Red Pigment, Excretes a Killer Toxin, and Form No Froth Head in the Fermenting Mash

Abstract

A non-foaming mutant of the sake yeast strain K-10 was isolated by the froth flotation method. Cells of the mutant were mutagenized by UV irradiation, and an adenine auxotroph K 10 NFP 1 was isolated after the nystatin screenig. The K₁ type killer trait was brought into K 10 NFP 1 strain through protoplasut fusion with a kar 1 (karyogamy defctive) strain harboring the K₁ type killer plasmids, and thus bred a strain K 10 NFP 1 which showed the three characters mentioned above. K 10 NFP 1 strain accumulated a red pigment in the cells and made the sake mash pink without allowing the outgrowth of wild yeast contaminants.