A mutant strain (KL-38) of Aspergillus oryzae was obtained by UV irradiatio
n. Phytase activity of KL-38 in molded rice (koji rice) was about 2.7-fold
of that obtained from the parent strain (BP-1). Phytase activity of KL-38 i
n the submerged culture was similar to that of BP-1. Two types of phytase w
ere produced from koji culture: phytase I (Phy I) was produced during incub
ation of both koji and submerged cultures, and phytase II (Phy II) was obta
ined only from koji culture. Phy II production was increased in KL-38 compa
red with BP-1, whereas the production of Phy I was similar for both KL-38 a
nd BP-1. This finding indicates that A. oryzae has at least two types of ph
ytase isozyme.