Abstract:The characterization of protease from Aspergillus oryzae has a significant impact on soy sauce quality.In this study,an Aspergillus oryzae CICIM F0899 capable of producing neutral protease was investigated.Morphology of Aspergillus oryzae F0899 and Aspergillus oryzae 3.042 were imaged by SEM.The conidial head of Aspergillus oryzae F0899 was relatively smaller than that of the strain 3.042.Its conidia were larger than that of the 3.042 strain.In addition,properties of the protease secreted by this strain were tested and compared with profiles of an industrially strain Aspergillus oryzae 3.042.The results showed that the optimum temperature for the extracellular protease from F0899 was 60℃,with the stable temperature range between 20~40℃.The optimal pH was 8.0,with the stable pH range between 6.0~8.0.It could tolerate 18% sodium chloride and still retains 20% activity,which is as high as 2.2 times than that from 3.042 under the same condition.The activity of the enzyme was severely inhibited by Ag+,but affected by Fe3+ only slightly.Therefore,protease from Aspergillus oryzae F0899 can bear higher temperature,lower pH and higher NaCl concentration than that from 3.042.
