A Generalized Kinetic Framework Applied to Whole-Cell Bioelectrocatalysis in Bioflow Reactors Clarifies Performance Enhancements for Geobacter Sulfurreducens Biofilms

Graphical Abstract

Go with the flow: Cell-based biotransformations are well-known for food and beverage production, but only recently has the domain of “whole-cell biocatalysis” become a recognized area of research. Here, a flow-adapted version of Michaelis–Menten kinetics is used to study whole-cell catalysis in flow. This proof-of-principle monitors the bioelectrocatalysis of a Geobacter sulfurreducens biofilm by using a three-electrode microfluidic flow reactor. Measured turnover rates are interpreted based on standard parameters such as K_M and ϵ, and point to an increase in accessible electrocatalytic bacteria with flow.

Abstract

A common kinetic framework for studies of whole-cell catalysis is vital for understanding and optimizing bioflow reactors. In this work, we demonstrate the applicability of a flow-adapted version of Michaelis-Menten kinetics to an electrocatalytic bacterial biofilm. A three-electrode microfluidic biofilm flow reactor measured increased turnover rates by as much as 50 % from a Geobacter sulfurreducens biofilm as flow rate was varied. Based on parameters from the applied kinetic framework, flow-induced increases to turnover rate, catalytic efficiency and device reaction capacity could be linked to an increase in catalytic biomass. This study demonstrates that a standardized kinetic framework is critical for quantitative measurements of new living catalytic systems in flow reactors and for benchmarking against well-studied catalytic systems such as enzymes.