Marco Scheidle1, Barbara Dittrich2, Markus Jeude1, Simon Curvers3, Doris Klee2, and Jochen Büchs4. (1) AVT - Aachener Verfahrenstechnik - Chair of Biochemical Engineering, RWTH Aachen University, Worringerweg 1, Aachen, Germany, (2) Textile Chemistry and Macromolecular Chemistry, RWTH Aachen University, Pauwelsstr. 1, Aachen, Germany, (3) AC Biotec, Nattermannalle 1, Köln, Germany, (4) AVT - Chemical Engineering, RWTH Aachen University, Worringerweg 1, Aachen, Germany
Many microbial systems which are used for industrial processes show overflow metabolism at elevated carbon source concentrations and/or display catabolite repressed product formation. In these cases, batch operation is not the preferred operation mode and therefore, these cultures are run in fed-batch at larger scales. However, for the screening of production strains batch mode is still state of the art. Moreover, for screenings high buffer concentrations are used, since dosage of acids and bases are costly and difficult in high throughput applications. These high buffer concentrations may lead to osmotic growth inhibition. Due to the different physiological conditions in the cultivation modes, it is quite questionable whether in batch operation mode suitable strains can be selected for large scale fed-batch operation. A new polymer based slow-release system was developed to perform small scale fed-batch cultivations in shake flasks and micro titre plates (MTP) without the usage of additional equipment [Jeude et al. 2006]. Glucose or pH controlling reagents, e.g. sodium carbonate, are embedded in a polymer matrix and can be fed into a cultivation medium with defined release kinetics.
This presentation deals with applications of the slow-release technique. For example Hansenula polymorpha screenings in batch and fed-batch mode are compared. In addition it is shown that a reduction of buffer concentrations in Escherichia coli mineral medium can be achieved by slow-release of sodium carbonate.
Jeude et al. (2006). "Fed-batch mode in shake flasks by slow-release technique." Biotechnol. Bioeng. 95(3): 433-45.
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