Respiratory Deficient Mutants of Bottom Brewer's Yeast. I. Frequencies and Types of Mutant in Various Strains

Abstract

Four strains of bottom brewer's yeast used in Czech breweries did not differ substantially from one another in their frequencies of spontaneous respiratorydeficient (RD) mutants as tested by the triphenyl tetrazolium chloride (TTC) overlay technique. These frequencies amounted to 1.1-1.4% of the total viable cell number after cultivation in bottom layers of wort. The strain which had the highest rate of aerobic growth gave a spontaneous mutation frequency of 0.5% in shaken cultures.In comparison with the TTC overlay technique, YVL-Difco-agar with brom cresol green gave lower estimations of the frequency of production of spontaneous RD mutants.The RD mutants isolated can be divided into 11 groups on the basis of their cytochrome content (particularly cytochromes 6 and c) after aerobic growth.Of the 34 RD isolates tested, only 3 produced considerable numbers of revertants to respiratory sufficiency. These 3 mutants were derived from the same original strain, had the same cytochrome type, and had very slow growth rates.All RD mutants isolated had slower growth rates under aerobic conditions and reduced fermentation rates in static cultures in comparison with the parent types.

125thAnniversary Review: Developments in brewing and distilling yeast strains

“…However, if the mutation weakens the yeast, the mutated strain will be unable to compete and will soon be outgrown by the non‐mutated yeast population. The characteristics that are routinely encountered resulting from mutation that can be harmful to a wort fermentation are: the tendency of yeast strains to mutate from flocculent to non‐flocculent ; the loss of ability to ferment maltotriose ; the presence of respiratory deficient (RD, ‘petite’) mutants .…”

A mutant of Saccharomyces cerevisiae temperature sensitive for flocculation. Influence of oxygen and respiratory deficiency on flocculence

“…The petite condition has been reported to affect flocculence (13). Petites of C75-M24, C77-M24-23, and 169 were induced with ethidium bromide (cf.…”

“…Mutation to respiratory deficiency (the petite condition) has been reported to affect the flocculence of Saccharomyces carlsbergensis strains (5,13). It has also been reported that petites of the S. cerevisiae strain 169 are nonflocculent (14).…”

The Microbiology of Malting and Brewing

“…Repercussions include changes in flocculation and utilization of maltotriose (18). Yeast drift can also arise through the partial or complete loss of mitochondrial DNA, leading to the production of so-called "petites" (19)(20)(21). Although alcoholic fermentation is anaerobic, meaning there is no role for a respiratory function in mitochondria, the latter organelles do have other metabolic functions in brewery fermentations (22)(23)(24).…”