A paradigm shift for biocatalytic microreactors: Decoupling application from reactor design

Abstract

Microreactors have been successfully applied to execute a broad range of biotransformations in flow. However, microreactors have typically been designed with a specific biotransformation or a specific biocatalyst immobilization method in mind, constraining their wider applicability. Furthermore, their design is typically either applicable for whole-cell or for enzyme biocatalysis, but not for both. We present a novel microreactor design which offers cartridge-like insertion of both immobilised enzymes and cells. A T-shaped lid opens and closes the reaction chamber (whilst leaving the rest of the microreactor unchanged), enables the easy insertion of immobilised biocatalysts, and thus allows the user to configure different reactor types. We demonstrated this novel concept showing three different reactor types: a hydrogel microreactor containing entrapped E. coli cells overexpressing transketolase (volumetric productivity of 2.23 ± 0.83 mmoll-ERY Lvoid1 min1), a packed-bed microreactor containing commercial beads with immobilised Candida antarctica lipase B (volumetric productivity of 317.69 ± 96.74 mmolBB Lvoid1 min1), and a micropillar microreactor containing surface-immobilised ω-transaminase (volumetric productivity of 0.08 ± 0.02 mmolACP Lvoid1 min1). The proposed design showed consistency and robustness for 10 consecutive T-shaped lid ‘open and close’ cycles and withstood the pressure of at least 4 bar. Design analysis further included Computational Fluid Dynamics models and Residence Time Distribution measurements. The presented design offers a standardised approach for multiple applications, underpinning process development and paving the way for off-the-shelf microreactor technology for biocatalysis.