| dc.description.abstract | Aspergillus unguis and Penicillium citrium were isolated from weasel coffee and had been studied for pectinase and cellulose production before. Protease is one of three largest groups of enzyme that affect to the aroma of coffee, however; it has not been researched and fully understood especially two above fungi. The main purpose of this study was to synthesize the protease production by A. unguis and P. citrinum. The solid state fermentation was carried out by using rice bran as substrate. In addition, protease activity was estimated by using casein as substrate followed the Lowry method. The influence of process parameters such as initial moisture, pH, incubation time and supplemented nutrients including nitrogen source, carbon source and mineral were evaluated. It was found that the medium that contained supplemented nutrients including peptone, maltose, ZnSO4 at moisture content was 60% for 62hrs produced highest protease by Aspergillus unguis and Penicillium citrinum produced maximum protease in medium that contained nutrient sources including peptone, sucrose, KH2PO4 at moisture was 70% for 90h. This enzyme was stable at acidic pH and produced at optimum pH=5-6. The maximum production of protease by Aspergillus unguis and Penicillium citrium during the course of study were 65.89±2.14 UI/ml and 91.78±2.01 UI/ml, respectively. These results indicated that these fungi showed a potential for production of low cost acidic protease by using inexpensive substrate as rice bran.
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Keywords: Aspergillus unguis, Penicillium citrium, protease, solid state fermentation. | en_US |
