Abstract The autolysis of yeast cells has practical
implications in the production of fermented foods and
beverages and flavourants for food processing. Protein
and RNA degradation during yeast autolysis are well
described but the fate of DNA is unclear. Yeast cells
(Saccharomyces cerevisiae) were autolysed by incubating
suspensions at 30–60C (pH 7.0), and at pH 4.0–7.0
(40C) for 10–14 days. Up to 55% of total DNA was
degraded, with consequent leakage into the extracellular
environment of mainly 3¢- and 5¢-deoxyribonucleotides,
and lesser amounts of polynucleotides. The rate and
extent of DNA degradation, composition of the DNA
degradation products and DNase activity were affected
by temperature and pH. The highest amount of DNA
degradation occurred at 40C and pH 7.0, where the
highest DNase activity was recorded. DNase activity
was lowest at 60C and pH 4.0, where the proportion of
polynucleotides in the degradation products was higher.
Keywords Autolysis Æ Yeasts Æ Saccharomyces
cerevisiae Æ DNA degradation