Mixing Characteristics of Submerged Fungal Fluid in a Flexible Stirred Mixer System

Abstract

This study was focused on the intensification of alpha amylase activity by fungi. Submerged culture of Aspergillus oryzae as a non-Newtonian fluid with a complex rheology and morphology was used. The aim of this study was to enhance the hydrodynamics of the biological fluid for an improvement in cell-gas mass transfer. Therefore, we investigated the advantages of using a Swingstir^® agitator that features an angular motion. Results showed that mixing time, mixing energy, and power-law model parameters using the Swingstir^® all were lower than when a double Rushton turbine (DRT) was used at the same level of power consumption. The Swingstir^® can produces a homogeneous and periodic-flow distribution. Moreover, K_La could be controlled throughout the fermentation process. Also, the morphology of pellets agitated by Swingstir^® had a positive effect on mass transfer intensification, because the stress is applied by flexible shaft movement instead by the blade tip of impeller. Consequently, the alpha amylase activity and cell growth of a culture agitated by Swingstir^® were higher than that developed using a DRT.