J. Fujita et al., Critical importance of phytase for yeast growth and alcohol fermentation in Japanese sake brewing, BIOTECH LET, 23(11), 2001, pp. 867-871
The high phytase producing mutant of Aspergillus oryzae (KL-38) previously
isolated was employed for koji making, and the produced koji rice then supp
lied for sake brewing. The alcohol fermentation was improved compared to th
at with the parent strain (A. oryzae BP-1). The effects of two phytase isoz
ymes (Phy I and Phy II) produced by A. oryzae on yeast growth and inorganic
phosphate liberation were investigated using a synthetic medium containing
phytic acid as a sole phosphate source. Yeast growth and the liberation of
inorganic phosphate were both enhanced by the combination of Phy I and Phy
II at a ratio of 1 to 3, which was compatible with the production ratio in
KL-38. Based on these results, phytase plays important role in sake brewin
g, and that the maximum inorganic phosphate liberation from phytic acid can
be obtained by a suitable combination of Phy I and Phy II.