10 Continuous-flow biocatalysis with enzymes and cells

Abstract

The advantages of synthetic chemistry performed in continuous flow synergize with the benefits conferred by biocatalysis, including reactions with greener, milder, lower temperatures, and aqueous conditions. Furthermore, the fine control over reaction conditions in continuous flow can solve inherent challenges associated with catalysis by enzymes, such as substrate and product inhibition. Cells and enzymes also benefit from the improved mixing, mass transfer, thermal control, pressurized processing, decreased variation, automation, along with in-line product analysis and purification conferred through continuous flow. Thus, the combination of continuous flow and biocatalysis has emerged as a highly effective approach for creating diverse synthetic targets. Examples include immobilized enzymes and whole cells in continuous flow for the synthesis of pharmaceuticals, chemicals, and materials. Challenges to continuous-flow biocatalysis surveyed in this chapter include immobilization methods, the necessity to regenerate cofactors for cell-free biocatalysis, and optimization of biosynthetic steps with highly divergent conditions in flow.

Wall‐Immobilized Biocatalyst vs. Packed Bed in Miniaturized Continuous Reactors: Performances and Scale‐Up

“…[91] Flow reactors overcome this challenge, with a fine control over reaction conditions close to the enzyme location and with a constant removal of the product. [92] This challenge may also justify some specific technical choices like the use of membranes when enzymatic products can be continuously removed from the reaction mixture based on size-exclusion separation, reducing product inhibition effects and the formation of side-product (i. e. peptide and oligosaccharide production). [93,94] Optimal operating conditions and appropriate reactor design, integrating kinetic parameters, can be computationally guided to avoid timeconsuming and expensive experiments.…”

“…To be noted that sub‐optimal performances encountered with batch process can be assigned to product and/or substrate inhibitions at elevated concentrations [91] . Flow reactors overcome this challenge, with a fine control over reaction conditions close to the enzyme location and with a constant removal of the product [92] . This challenge may also justify some specific technical choices like the use of membranes when enzymatic products can be continuously removed from the reaction mixture based on size‐exclusion separation, reducing product inhibition effects and the formation of side‐product (i. e. peptide and oligosaccharide production) [93,94] .…”

Magnetically agitated continuous-flow tube reactors with aspartate ammonia-lyase immobilized on magnetic nanoparticles

“…One possible aid and tool for enabling more and more efficient processes is the use of biocatalysis. 1,2 The immobilization of biocatalysts 3,4 and the advanced reactor technologies in biocatalysis [5][6][7] can contribute to the improvement of more efficient and less environmentally burdensome methods.…”

“…19 Immobilized enzymes in microfluidic systems open new opportunities in diagnostic, synthetic, and analytical applications. 5,6 Among the possible manifestations, MNPbased microreactors offer a unique opportunity to develop modular micro-systems with special benefits such as the ease of replacing the exhausted MNP biocatalyst with fresh or even other type of MNP biocatalyst. 22,23 For instance, cholesterol determination was performed in a tubular device with coimmobilized cholesterol esterase/cholesterol oxidase-MNPs affixed to a permanent magnet.…”