In this study, the strain named A. oryzae CH93 was isolated
from soil samples. SEM scanning revealed some morphological features
of this fungal strain. A. oryzae is a filamentous fungi [42].
According to the data presenting herein, we concluded that best
conditions for the production fungal protease from A. oryzae CH93
were addition 1% w/v of glucose as carbon source and 1% w/v
of yeast extract as nitrogen source and incubation of the strain
at 28 ◦C and pH 6 for a period of 96 h. The key properties of
the A. oryzae CH93 protease were having a molecular weight of
47.5 kDa, the optimum pH and temperature of 8 and 50 ◦C, respectively.
Because of this protease was not sensitive to be inhibited by
PMSF, therefore the enzyme couldn’t belong to serine proteases.
Meanwhile, 2-mercaptoethanol (2-ME) and EDTA led to decrease
protease activity, whilst, the enzyme activity increase in the presence
of acetone and isoamyl alcohol and decreased in the presence
2-propanol, isopropanol, and DMSO. Hexane (both concentrations15% and 30%), chloroform (at 15% concentration) and toluene (at
30% concentration) have not significantly affect on protease activity.
The half-life of the protease at optimum temperature was
100 min. The best substrate was casein with the maximum velocity
(Vmax) of 0.1411 ± 0.004 g/min and Km of 2.432 ± 259 g/ml.
In conclusion, the protease isolated from A. oryzae CH93 showed
some new biochemical characteristics that have not been reported
until now from Aspergillus genus.