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%0 Thesis
%A Lüchtrath, Clara Agnes
%T Advancing diffusion-driven small-scale fed-batch technologies
%I RWTH Aachen University
%V Dissertation
%C Aachen
%M RWTH-2025-04706
%P 1 Online-Ressource : Illustrationen
%D 2025
%Z Veröffentlicht auf dem Publikationsserver der RWTH Aachen University
%Z Dissertation, RWTH Aachen University, 2025
%X The fed-batch cultivation mode is the most prevalent in industrial bioprocesses, as it effectively mitigates a multitude of detrimental phenomena, including overflow metabolism, mixed acid formation, and oxygen limitation. To achieve the most efficient industrial-scale bioprocess, it is essential that the process development is performed in fed-batch. Consequently, a variety of fed-batch technologies for microtiter plates and shake flasks have been developed. In this study, two bioreactor systems were employed: the commercially available diffusion-driven FeedPlate® for microtiter plates and the membrane-based fed-batch system for shake flasks. In the FeedPlate® system, the glucose is embedded in a silicone matrix and released upon contact with the culture medium. In the membrane-based fed-batch shake flask, the feed solution is stored in a glass reservoir connected to a membrane-sealed diffusion tip. The feed solution is released upon contact with the culture broth. This thesis employs diffusion-driven fed-batch techniques to investigate enzyme production in the fast-growing host Vibrio natriegens. Given the striking overflow metabolism and mixed acid formation, it was hypothesized that fed-batch fermentation would result in higher enzyme yields. Induction profiling revealed notable dependencies on the yield in batch processes, which were not observed in fed-batch processes. Moreover, the membrane-based fed-batch shake flask was applied to simulate a co-cultivation of Synechococcus elongatus and Ustilago maydis. To investigate the impact of a co-culture wherein S. elongatus releases minimal quantities of sucrose, the growth of U. maydis under these conditions was monitored. It was demonstrated that U. maydis exhibits growth under conditions with feeding rates of 1 mg/h. To further exploit the potential of membrane-based feeding in shake flasks, the established feeding system was implemented in perforated ring flasks. The combination of membrane-based feeding and the novel flask geometry enables high oxygen transfer rates even at elevated filling volumes and lower shaking frequencies. Therefore, it could be a useful tool for screening applications. Additionally, a feasibility study was conducted to examine if an increasing feed rate can be established in the membrane-based fed-batch shake flask by introducing an intermediate chamber. For the feasibility study, a mathematical model was created. Parameter variation within this model revealed that increasing feed rates during a cultivation process are not feasible with the current design of the 3-chamber system. The presented work highlights the potential of diffusion-driven feeding systems. In future works, these systems can help to improve strain screening, process development and the research of co-cultivations.
%F PUB:(DE-HGF)11
%9 Dissertation / PhD Thesis
%R 10.18154/RWTH-2025-04706
%U https://publications.rwth-aachen.de/record/1011757