132 microorganisms, isolates from soil and decayed fruits, were tested
for phytase production. All isolates intensively producing active ext
racellular phytase were of fungal origin. The most active fungal isola
tes with phytase activity were identified as Aspergillus niger. At the
end of the growth phase, the extracellular phytase activity produced
by A. niger strain 92 was 132 nkat/mL, with strain 89 it was 53 nkat/m
L. In both strains the extracellular enzyme activity exhibited two mar
ked activity optima at pH 1.8 and 5.0 and a temperature optimum at 55
degrees C.