Efficient extracellular electron transfer (EET) is critical to harnessing bacteria like Shewanella oneidensis MR-1 in microbial electrochemical systems (MESs) aimed at sustainable energy production, environmental remediation, and resource recovery. This study investigates how palladium ions (Pd2+), which are of significant interest for catalysis and resource recovery, impact the bioelectrocatalysis of S. oneidensis MR-1 using electrochemical, transcriptomic, and microscopic methods. Pd2+ exposure significantly increased the observed current via EET, which correlated with substantially increased viable biofilm formation on the electrode. Transcriptomics revealed a coordinated cellular response, including upregulation of genes facilitating EET (the Mtr pathway), metabolism, motility, and biofilm processes, alongside downregulation of competing pathways. Cellular reduction of Pd2+ to palladium nanoparticles, mainly near the outer membrane, was confirmed via microscopy. Pd2+ boosts S. oneidensis MR-1 bioelectrocatalysis through the combined effects of promoting biofilm development and upregulating essential cellular pathways, informing fundamental strategies for enhanced MESs targeted for sustainable engineering, bioremediation, and resource and material recovery applications.

Missouri S&T has been awarded a $19.8 million collaborative agreement to renew the National Science Foundation’s Center for Synthetic Organic Electrochemistry. This chemical innovation center will be ...

We describe complete lactate electrooxidation in an enzymatic biofuel cell that combines the catalytic action of the bimetallic composite Ru@Pt-CNT and the enzyme oxalate oxidase (OxOx). The Ru@Pt-CNT...

Bifurcating enzymes employ energy from a favorable electron transfer to drive unfavorable transfer of a second electron, thereby generating a more reactive product. They are therefore highly desirable in catalytic systems, for example, to drive challenging reactions such as nitrogen fixation. While most bifurcating enzymes contain air-sensitive metal centers, bifurcating electron transfer flavoproteins (bETFs) employ flavins. However, they have not been successfully deployed on electrodes. Herein, we demonstrate immobilization and expected thermodynamic reactivity of a bETF from a hyperthermophilic archaeon, Sulfolobus acidocaldarius (SaETF). SaETF differs from previously biochemically characterized bETFs in being a single protein, representing a concatenation of the two subunits of known ETFs. However, SaETF retains the chemical properties of heterodimeric bETFs, including possession of two FADs: one that undergoes sequential 1-electron (1e) reductions at high E° and forms an anionic semiquinone, and another that is amenable to lower-E° 2e reduction, including by NADH. We found homologous monomeric ETF genes in archaeal and bacterial genomes, accompanied by genes that also commonly flank heterodimeric ETFs, and SaETF’s sequence conservation is 50% higher with bETFs than with canonical ETFs. Thus, SaETF is best described as a bETF. Our direct electrochemical trials capture reversible redox couples for all three thermodynamically expected redox events. We document electrochemical activity over a range of pH values and reveal a conformational change coupled to proton acquisition that affects the electrochemical activity of the higher-E° FAD. Thus, this well-behaved monomeric bETF opens the door to bioinspired bifurcating devices or bifurcation on a chip.

Published research on topics of current scientific interest.

Light-powered microelectronics enable high-throughput experimentation

Published research on topics of current scientific interest.

Degradation tests represent a significant bottleneck in electrochemical technology development, occasionally requiring tens of thousands of hours. Thus, reliable degradation forecasting in a short time frame is a game-changer in accelerating the establishment of future electrochemical devices. Herein, we show a multidimensional kinetic model for electrocatalyst degradation by quantifying the relationship among potential, current, and time, applicable under various conditions. Aiming to predict reliable degradation behaviors in shorter experimental timeframes and inspired by modern weather forecasting methods, we integrated Bayesian data assimilation with our model to expedite multidimensional parameter optimization. Consequently, we achieved accurate and robust forecasting of electrocatalyst lifetime by employing oxygen evolution reaction as a representative system: it takes just 300 h to obtain the final lifetime of close to 1000 h even with environmental noise. This data-driven approach can accelerate our understanding of the microscopic electrochemical mechanisms and simultaneously directly bridge this understanding to develop next-generation energy technologies.

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