Project Details
Projekt
Investigation and modeling of the mechanical and surface-induced stress on pellets of filamentous microorganisms on Lechevalieria aerocolonigenes
Subject Area
Mechanical Process Engineering
Biological Process Engineering
Biological Process Engineering
Term
from 2016 to 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 315457657
The projects aim is to numerically and experimentally investigate the biotechnological process parameters of filamentous microorganisms cell morphology and its production behaviour in particle-induced cultivations. This enables the model-based selection of optimal particles (material, size, concentration) to increase production in these cultivations. This is demonstrated with filamentous growing Lechevalieria aerocolonigenes which produces the secondary metabolite rebeccamycin with antibiotic and antitumor properties in pelleted form. In the first funding period glass particle (macro particles) addition to a 250 mL shake flask led to pellet enlargement and a porous structure with increasing particle size and concentration and thus increasing mechanical stress. With a further increase in mechanical stress, the pellets became smaller and denser due to pellet erosion and break-up. The porous pellet structure improves substrate penetration and rebeccamycin production. The results show that product yields can only be predicted by characterizing the stress energies and that there is a complex correlation of particle size, density, concentration and shape. Using the CFD-DEM-simulation method, stress energy distributions of glass bead collisions in shake flasks could be determined, where the shear stress between particle and flask wall are the most significant stress component. Increased rebeccamycin concentration by addition of surface modified micro particles (e.g. talc) is suspected to be caused by surface effects through which the particles are attached to the hyphae and are incorporated into the pellets during growth. Thus, the pellet structure after addition of surface-modified glass particles will be a key aspect within the second funding period by extending the measurement methodology (µCT, O2-microelectrode technology). In the bioreactor, pellet growth and the stirrer-induced stress are examined in detail. Furthermore, a single pellet with its growth and induced mechanical stress is simulated. Therefore, the micromechanical behaviour of the hyphae and pellets, respectively, is characterized using a nanoindenter. The further development of existing population balance models is used to characterize pellet erosion and break-up.
DFG Programme
Priority Programmes
