Intensifying the Fermentation of Aspergillus oryzae in a Stirred Bioreactor Using Maxblend Impeller

Background: The intensification of fermentation in stirred bioreactors is an attractive approach for commercial interests and industries that work with biochemical products. Alpha amylase is an enzymatic bio-products that is produced largely from Aspergillus oryzae. Using adaptable agitator can be an efficient way for stirred fermentation. Objective: This study, concentrated on enhancing the mixing process in order to intensify Aspergillus oryzae fermentation. A straight type of Maxblend® impeller was used as an agitator to investigate the incubation parameters compared with the use of a 6-blade double Rushton turbine. Method: Stirred fermentation was done in batch condition. Effect of flow pattern of mixing on fermentation parameters was investigated after each sampling. Results: The results showed that the Maxblend® significantly intensified both enzyme activity and growth rate at low and moderate rates of power consumption (P). The main reason for the decreases in the growth rate and the enzyme activity during agitation by the Rushton turbine at low and high Pv was the lack of oxygen and mycelial damage, respectively. Additionally, use of the Maxblend® significantly intensified the KLa at low and moderate rates of power consumption. Conclusion: Axial and uniform mixing by Maxblend® impeller was resulted in improving the fermentation characteristics and enzyme activity.