Effects of fluid dynamic induced shear stress on fungal growth and morphology

Industrial applications of filamentous microorganisms become more and more relevant for example for the production of pharmaceuticals. Therefore, pellet morphology is often requested. Knowledge about pellet growth behaviour at different fluid dynamic conditions is important, because many production processes are influenced by morphology. Morphology itself is influenced by the fluid dynamic conditions in a bioreactor. In the present study, pellet growth of Aspergillus niger AB1.13 was studied under different fluid dynamic conditions. A new experimental set-up was designed to guarantee comparability and reproducibility. Kinetic parameters of pellet growth were correlated with energy input and the maximum shear rate.The present work shows that kinetic parameters depend on the fluid dynamic conditions. Additionally, it could be demonstrated that for model development a correlation with the local maximum shear rate is of relevance especially in relation to transferability to other reaction systems with different set-up.