Enzymatic versus Microbial Bio‐Catalyzed Electrodes in Bio‐Electrochemical Systems

Abstract

Catalyses of electrode reactions by oxidoreductases or living electroactive bacteria are compared and recent advances reviewed. The relation between the biological and nevertheless inert nature of enzymes and the living machinery of electroactive microbes is discussed. The way these biocatalysts may be electrically contacted to anodes or cathodes is considered with a focus on their immobilization at electrodes and on the issue of time stability of these assemblies. Recent improvements in power output of biofuel cells are reviewed together with applications that have appeared in the literature. This account also reviews new approaches for combining enzymes and living microbes in bioelectrochemical systems such as reproducing microbial metabolisms with enzyme cascades and expressing oxidoreductases on genetically engineered microbes. Finally, the use of surface chemistry for studying the microbe-electrode interface and bioelectrodes with cell organelles, such as mitochondria, or with higher organisms, such as yeasts, are discussed. Some perspectives for future research to extend this field are offered as conclusions.

A quantitative method to evaluate microbial electrolysis cell effectiveness for energy recovery and wastewater treatment

“…C E is an established parameter to evaluate how efficient the chemical energy stored in the wastewater was converted into electrical energy, or in other words, how much of the removed COD was converted into electrons. However, the main function of the MECs for wastewater treatment is COD removal [25,26] and minimizing overall energy usage for the process. Therefore, it makes sense to evaluate the process on the basis of electrical energy input per kg of removed COD (W EL ).…”

Electrocatalytic Carbohydrate Oxidation with 4-Benzoyloxy-TEMPO Heterogenised in a Polymer of Intrinsic Microporosity

“…Electrocatalytic oxidation of carbohydrates, especially for glucose derivatives, is of considerable interest in conjunction with sensing [1,2], bio-fuel cell development [3,4], and for electrosynthetic transformations [5]. Recent progress for example in multi-catalyst "cascade" catalytic systems offers new promise for better performance in complex multi-electron reactions such as glycerol oxidation [6].…”

Monophyletic group of unclassified γ- Proteobacteria dominates in mixed culture biofilm of high-performing oxygen reducing biocathode

“…The cathode potential was fixed at +0.150 V vs. Ag/AgCl using a potentiostat (IVIUM, The Netherlands). The pH was controlled at 7.0 ± 0.5 as previously described [8]. Water evaporated from the catholyte was replenished using demineralised water.…”

“…The open access of micro-organisms to the electrode and the availability of nutrients from the environment are two boundary conditions which allow operation of mixed culture oxygen reducing biocathodes. Performance of oxygen reducing biocathodes is determined by a wide range of parameters which include: cathode (over)potential, type of biocatalyst (enzyme, pure culture or mixed culture) [8], mass transfer of reactants and products, availability of essential nutrients, buffer capacity, temperature, electrode configuration and materials [6,[9][10][11][12][13]. While biological oxygen reduction is a common physiological trait, i.e.…”