Statistical Optimization of Thermostable α-Amylase Production by a Newly Isolated Rhizopus oryzae Strain FSIS4 Using Decommissioned Dates

A new Rhizopus oryzae strain FSIS4 isolated from wheat seed cultivated in Algerian Sahara was evaluated for the production of a thermostable α-amylase enzyme. Medium components were optimized by a statistical approach for the optimal production of α-amylase using an agro-industrial residue (decommissioned dates). The Plackett–Burman design was performed to screen the fermentation variables and response surface methodology for optimizing the significant factors affecting the production. The optimum levels for maximum production of α-amylase (approx 10,151 IU) were determined. A 1.8-fold increase of production was obtained in comparison to the non optimized medium. Partial characterization of the enzyme showed optimal temperature and pH at 60 °C and 5.0, respectively. The enzyme was found to be stable at 80 and 90 °C, with a half-life of 165 and 105 min, respectively. According to the large literature, this is the first report on the production of α-amylase by the thermophilic R. oryzae strain FSIS4. The thermo and pH stability of the α-amylase suggest its wide application in the food and pharmaceutical industries.