Towards the integration of fermentation and crystallisation
Special Symposium - EPIC-1: European Process Intensification Conference - 1
EPIC-1: Intensified Plants & Process Integration (IPPI)
Keywords: bioprocess integration, industrial fermentation, crystallisation, product inhibition, process improvement
Industrial fermentation processes demand high product concentrations in order to be commercially interesting. High product concentrations during fermentation not only translate in higher productivity, but are also linked to simpler and more efficient downstream processes. Currently, high product concentrations can be achieved by several tools provided by modern biotechnology. However, factors such as product toxicity to the micro-organism or product degradation continue to be limiting. In these cases, product recovery during fermentation may be beneficial. In this work, we evaluate product recovery by crystallisation, since most chemicals produced by fermentation are commercialised as solids. In this way, the resulting integrated process should lead to higher fermentation productivities (by removing product toxicity and/or degradation) and reduced downstream operations (by recovering the product already in crystal form), without requiring the use of auxiliary materials.
As a case study we selected the production of the amino acid L-Phenylalanine (Phe) by an engineered strain of Escherichia coli. Phe biosynthesis suffers from feedback inhibition, which limits the productivity of the system. Since Phe is still soluble at fermentation conditions, recovery of product crystals might be possible by means of an external loop. The development of the concept for this case study is discussed based on modelling and experimental work. Three points are stressed: the metabolic capabilities of the micro-organism, the crystallisation requirements (product specifications) and the integration of operations. Finally, the process performance is compared with that of the process without product recovery by crystallisation.
Presented Wednesday 19, 15:40 to 16:00, in session EPIC-1: Intensified Plants & Process Integration (IPPI).
