The industrial implementation of whole-cells and enzymes in flow biocatalysis microreactors is essential for the
emergence of a biobased circular economy. Major challenges concern the efficient immobilization of delicate enzymes
inside miniaturized reactors without compromising their catalytic activity. We describe the design and application of four
different immobilization techniques including self-immobilizing whole-cells and purified enzymes on magnetic
microbeads, as well as reactor modules manufactured by 3D printing of bioinks containing thermostable enzymes. To
increase the volumetric activity of our microreactors we furthermore developed and applied self-assembling all-enzyme
hydrogels with cofactor-regenerating capabilities. The resulting reactor formats have excellent operational stability times
of > 14 days and maximum space-time yields of > 450 g product/L-1day-1 paving the way for mild and effective
immobilization techniques of biocatalysts in microfluidic systems
