Abstract
Sixteen RD mutant strains of Saccharomyces carlsbergensis and Saccharomyces cerevisiae, which were isolated by spontaneous mutation, acriflavine treatment, and ultraviolet irradiation, were studied for their ability to produce citramalic acid in a chemically defined medium. It was found that all those RD "petite" mutants which were clearly judged to be respiration-deficient in any of the four criteria, i.e. oxygen uptake, coloration of colonies on BCG agar, TTC reduction, and lactate utilization, did accumulate citramalate abundantly (13 to 46mg per 100ml of medium). None of the seven parent normal strains tested produced citramalic acid. Some variants isolated on BCG agar (verdant and variegated types), which were positive in reducing TTC, were not able to produce citramalic acid.
RD mutant haploid strains of known cytochrome pattern (baker's yeast) were found to be divided into the citramalate formers and nonformers, but it was not possible to relate their citramalate-producing abilities to the kind of deficient cytochromes.
