Integrated development of fermentation and downstream processing or L -isoleucine production with Corynebacterium glutamicum

• Published in: Applied microbiology and biotechnology Vol. 46; no. 3; pp. 209 - 219
• Main Authors: Weuster-Botz, D., Karutz, M., Joksch, B., Schärtges, D., Wandrey, C.
• Format: Journal Article
• Language: English
• Published: 01-10-1996
• Subjects: Corynebacterium glutamicum
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s002530050807

Applying a genetic algorithm for the optimization of trace element composition in the medium for L-isoleucine production from glucose and DL- alpha -hydroxybutyric acid with Corynebacterium glutamicum resulted in a reduction of the byproduct L-valine. High L-isoleucine broth concentrations of 20 g/l within 72 h at an L-isoleucine/DL- alpha -hydroxy butyric acid yield of 70% (w/w) and an L-isoleucine/L-valine ratio of 100 were achieved, if closed-loop control of glucose and of DL- alpha -hydroxybutyric acid was applied. For the isolation of L-isoleucine from fermentation broth a specific downstream processing was developed and optimized up to semitechnical scale (ultrafiltration, reverse osmosis, first crystallization, active-carbon adsorption, electrodialysis, second crystallization). The economic model of this downstream processing, which was identified by coupling the mass balance and energy balance with the semi-empirical models of the unit operations, was used to quantify the isolation costs as a function of L-isoleucine concentration and L-isoleucine/L-valine ratio in the fermentation broth. A cost reduction for downstream processing from DM 55 to DM 25 (kg L-isoleucine) super(-1) and an improvement of the L-isoleucine yield in downstream processing from 48% to 80% was achieved using this economic model as the objective function to be minimized by the fermentation process (scenario: production of 70 tonnes L-isoleucine/year).