Multi-product cell factory

Apart from new catalytic methods, cascade conversions require new process technologies, such as in situ product recovery, reactor design, and compartmental-ization. In the long term, part of the present-day stoichiometric chemistry as well as bio- and chemocatalytic conversions in multi-step syntheses will gradually be replaced by cascade catalysis in concert, and full fermentations by cell factory design, or combinations thereof (Fig. 13.17). 

Optimization of a Multi-Product Microbial Cell Factory for Multiple Objectives - A Paradigm for Metabolic Pathway Recipe... 

Keywords Multi-product microbial cell factory. Mixed integer MOO (MIMOO), Metabolic pathway recipe, Pareto-optimal set. 

Optimization of a Multi-Product Microbial Cell Factory... 

Almost all works on optimization of a multi-product microbial cell factory focussed on a single objective (e.g., Schmid et al., 2004 Visser et al, 2004 Vital-Lopez et al, 2006). A common feature in these works is the pseudo-stationary assumption. Enzymatic reaction kinetics in a microbial cell factory are reversible and interdependent. In reality, the fluxes due to enzymatic reactions are never stationary. Given the limitations of a model, it is necessary to assume a pseudo-stationary state where some variables fluctuate about an averaged steady state within certain bounds. 

A cell of a living microorganism can be considered as a small factory consisting of different reactors containing different catalysts (enzymes). In this way, the cell can perform multi-step conversions without the need for recovery or purification of intermediate products. Through this so-called metabolic pathway, i.e. the consecutive conversion of the starting material into the end product, one fermentation can replace a multi-step chemical and/or catalytic procedure. In addition, as the enzymes are chiral catalysts, only one of the two optical isomers is produced. 

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