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

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.

Mainstreaming microfluidic microbial fuel cells: a biocompatible membrane grown in situ improves performance and versatility

“…where the initial acetate concentration at the inlet is given as [Ac] i (mol L −1 ), and the final acetate concentration after oxidation is given as [Ac] f . The acetate turnover rate dmol Ac dt (mol s −1 ) is the consumption of acetate per unit time, which can be calculated from the current: 26 dmol Ac dt…”

Reaction kinetics of anodic biofilms under changing substrate concentrations: Uncovering shifts in Nernst‐Monod curves via substrate pulses

“…worked at ‐0.4 V versus Ag/AgCl whereas Zarabadi et al. did not specify the applied anode potential during biofilm growth [ 27 , 28 ]. In literature, Monod constant values of non‐electroactive planktonically cultivated Escherichia coli and Saccharomyces cerevisiae vary over more than 2 and 3 orders of magnitude, and it should be stressed that the case of E. coli and S. cerevisiae does not stand alone [ 29 ].…”

“…Other papers stated similar values of K S between 0.59 and 2.86 mmol L −1 for acetate-fed anodic biofilms in continuously operated single-chamber reactors, but only Kretzschmar et al worked at similar anode potentials [26]. Lee et al worked at -0.4 V versus Ag/AgCl whereas Zarabadi et al did not specify the applied anode potential during biofilm growth [27,28]. In literature, Monod constant values of non-electroactive planktonically cultivated Escherichia coli and Saccharomyces cerevisiae vary over more than 2 and 3 orders of magnitude, and it should be stressed that the case of E. coli and S. cerevisiae does not stand alone [29].…”

Microbial fuel cell power overshoot studied with microfluidics: from quantification to elimination

“…Microfluidic microbial bioelectrochemical systems have been used to study the effect of flow rate, chemical composition of the nutrient solution, and other experimental conditions on measurable performance indicators, such as EAB electrical outputs power production, kinetic parameters, and EAB pH. [14][15][16][17] When applied to MFCs, certain efficiencies can be realized in a microfluidic format, such as reduced start-up time, ability to eliminate the need for ion exchange membranes, optimization of biofilm formation and improved outputs and assay studies via high parallelization. [18][19][20][21][22] The recent availability of microfluidic MFCs that are reliably operational over a timescale of months [23] provides the opportunity to finally study overshoot in mature MFCs vis-a-vis solution concentrations, convection and other related hydrodynamic effects under highly controlled conditions.…”