The performances of radial-axial flow (Rushton-Maxflo impellers) and axial-radial flow (Maxflo-Rushton impellers) mixers in the laminar-transitional flow regime were experimentally and numerically investigated with Newtonian and non-Newtonian fluids. The rheological properties for a fermentation broth consisting of the fungus Beauveria bassiana were studied under different hydrodynamic conditions in these systems. The bioreactor was a continuous stirred-tank reactor (CSTR), set at different stirring velocities. The rheology of the systems exhibited shear-thinning behavior which was modeled with the power law model. The experimental hydrodynamics and configuration modes were compared and simulated with a model fluid system and by numerical criteria (computational fluid dynamics). The R-M mode was found to be more efficient than the M-R rotating mode in terms of energy and homogenization time. The results will help in the optimization of scale-up production of these fungi.