Konstruktive Optimierung eines Fed-Batch-Schüttelkolbensystems

Abstract:
Profitable fermentation processes require optimal microorganisms which are preselected in primary screenings. Although the fed-batch mode is most frequent in biotechnological production processes, the batch mode is common in screening. The different modes often lead to different metabolism activities and, therefore, to false strain selection with fatal economic consequences. At the Chair of Biochemical Engineering at RWTH-Aachen University, a fed-batch system for shaking flasks has been developed. In this system, nutrient releases through a membrane from a reservoir into the culture broth. The continuous rotation of the diffusion tip with the culture liquid guarantees their permanent contact and the permanent nutrient supply of the organisms. Due to the use for offline cultivations and in the RAMOS system, two types of fed-batch flasks exist. The RAMOS-flasks were improved using an autoclavable bonding technique. The transparency was enhanced using glass instead of stainless steel reservoirs. Switching from melting to bonding the fed-batch shake flasks improved the geometric reproducibility and allowed to remove the “buffer zone” between the upper and lower part of the flask stump, thus reducing the flask volume. In addition, reservoirs don´t have to be individually adapted to each flask but can be interchanged between all flasks. The handling of the fed-batch-offline-flasks was simplified by the integration of a membrane as sterile barrier and for gas transfer into the cover plate. The membrane can be used several times and must not be replaced after each cultivation like the previous cotton plugs or cigarette filters. Finally, the gas exchange of fed-batch and standard shake flasks was determined.

Keywords:
fed-batch shake flask, construction, autoclavable glass adhesion technique