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Appl. Environ. Microbiol., 02 1995, 630-638, Vol 61, No. 2
AC Codon, JM Gasent-Ramirez and T Benitez
To clarify the role that respiration, the mitochondrial genome, and
interactions of mitochondria and nucleus play on sporulation and to improve
the sporogenic ability of several baker's yeasts, an investigation of the
effects of different media and culture conditions on baker's yeast
sporulation was undertaken. When standard protocols were followed, the
sporulation frequency varied between 20 and 60% and the frequency of
four-spore asci varied between 1 and 6%. Different presporulation and
sporulation media, the use of solid versus liquid media, and incubation at
22 versus 30 degrees C were checked, and the cells were collected from
presporulation media in either exponential or stationary phase. Best
results, yielding sporulation and four-spore ascus formation frequencies up
to 97 and 60%, respectively, were obtained by collection of the cells in
exponential phase from liquid presporulation medium with 10% glucose and
transfer of them to sporulation medium with 0.5% potassium acetate at 22
degrees C. Under these conditions, the most important factor was the growth
phase (exponential versus stationary) at which cells from presporulation
medium were collected. Changes in sporulation frequencies were also
measured after transfer of mitochondria from different sources to baker's
yeasts. When mitochondria from laboratory, baker's, and wine yeasts were
transferred to baker's and laboratory petite strains, sporulation and
four-spore ascus formation frequencies dropped dramatically either to no
sporulation at all or to less than 50% in both parameters. This transfer
also resulted in an increase in the frequency of petite mutant formation
but yielded similar growth and respiration rates in glycerol.(ABSTRACT
TRUNCATED AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
Factors which affect the frequency of sporulation and tetrad formation in Saccharomyces cerevisiae baker's yeasts [published erratum appears in Appl Environ Microbiol 1995 Apr;61(4):1677]
Departmento de Genetica, Universidad de Sevilla, Spain.
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