Betreuer: Cornelia Bähr
Integration einer zusätzlichen Diffusionsbarriere in ein membranbasierten Fed-Batch-Schüttelkolben-System zur Realisierung eines zeitverzögerten Einsetzens der Nährstoffzufuhr
Nowadays numerous products are biotechnologically manufactured and their share increases. The first step of bioprocess development is the primary screening with search for the best suited production strain. The screening is predominantly performed under batch conditions. By contrast, most of the production processes are operated in fed batch mode. Therefore, screening in fed batch mode would be advantageous. In this manner there would be a better reproducibility for the scale-up process and high performance strains would not get excluded in early screening stages. In this study, a reservoir based fed batch system for screening purposes should be optimized for a successful implementation of a delayed nutrient feeding. The goal was to avoid the nutrient accumulation at the beginning of the cultivation by the implementation of an additional diffusion barrier. For this reason felt was chosen as an appropriate material. With a refractometer system the diffusive flow of water and glucose were characterized. These release experiments demonstrated that a delay of the nutrient feeding was possible by using felt as an additional diffusion barrier. The diffusion resistance against water was lower than for glucose. Further experiments without a diffusion barrier showed a direct correlation between the glucose diffusion and the water reverse flow. The correlation was also dependent on the glucose concentration. In cultivation experiments the strain E. coli BL21 (DE3) pRhotHi-2-EcFbFP was used for the evaluation of the fed batch system. The increase of the glucose concentration in the reservoir leaded to a higher feed level. In addition, the pH and the buffer concentration of medium were adapted to the increased metabolic activity. In the last experiment it was shown that with the use of an additional diffusion barrier the glucose accumulation in the medium was reduced. In this way the results of the release experiments were confirmed.
fed-batch shake flask, delayed feeding, E. coli BL21 (DE3) pRhotHi-2-Ec FbFP