Bacteria able to transfer electrons metals are key agents in biogeochemical metal cycling, subsurface bioremediation, and corrosion processes. More recently, these bacteria have gained attention as the of from cell surface conductive materials can be used multiple applications. In this work, we adapted electrochemical techniques probe intact biofilms Shewanella oneidensis MR-1 sp. MR-4 grown by using a poised electrode an electron acceptor. This approach detected redox-active molecules...

The Mtr respiratory pathway of Shewanella oneidensis strain MR-1 is required to effectively respire both soluble and insoluble forms oxidized iron. Flavins (riboflavin flavin mononucleotide) recently have been shown be excreted by facilitate the reduction substrates. Other species tested accumulated flavins in supernatants an extent similar that MR-1, suggesting secretion a general trait species. External proposed act as electron shuttle metal chelator; however, at biologically relevant...

Shewanella oneidensis strain MR-1 is widely studied for its ability to respire a diverse array of soluble and insoluble electron acceptors. The breathe substrates defined as extracellular transfer can occur via direct contact or by shuttling in S. oneidensis. To determine the contribution flavin shuttles transfer, transposon mutagenesis screen was performed with identify mutants unable secrete flavins. A multidrug toxin efflux transporter encoded SO_0702 identified renamed bfe (bacterial...

Bioelectrochemical systems rely on microorganisms to link complex oxidation/reduction reactions electrodes. For example, in Shewanella oneidensis strain MR-1, an electron transfer conduit consisting of cytochromes and structural proteins, known as the Mtr respiratory pathway, catalyzes flow from cytoplasmic oxidative Reversing this drive microbial reductive metabolism offers a possible route for electrosynthesis high value fuels chemicals. We examined electrodes into determine feasibility...

Summary Four distinct pathways predicted to facilitate electron flow for respiration of externally located substrates are encoded in the genome Shewanella oneidensis strain MR‐1. Although share a suite similar proteins, activity only two these has been described. Respiration extracellular requires mechanism transfer from quinone pool cytoplasmic membrane terminal reductase enzymes on outer leaflet membrane. The four MtrA paralogues, periplasmic carrier cytochrome, and reductases MtrC...

Shewanella oneidensis strain MR-1 can respire using carbon electrodes and metal oxyhydroxides as electron acceptors, requiring mechanisms for transferring electrons from the cell interior to surfaces located beyond cell. Although purified outer membrane cytochromes will reduce both metals, S. also secretes flavins, which accelerate transfer metals electrodes. We developed techniques detecting direct by intact cells, turnover single voltammetry. Metabolically active cells attached graphite...

Anaerobic ammonium oxidation (anammox) bacteria contribute significantly to the global nitrogen cycle and play a major role in sustainable wastewater treatment. Anammox convert (NH4+) dinitrogen gas (N2) using intracellular electron acceptors such as nitrite (NO2−) or nitric oxide (NO). However, it is still unknown whether anammox have extracellular transfer (EET) capability with of electrons insoluble acceptors. Here we show that freshwater marine couple NH4+ graphene electrodes microbial...

ABSTRACT We developed a new method to measure iron reduction at distance based on depositing Fe(III) (hydr)oxide within nanoporous glass beads. In this “Fe-bead” system, Shewanella oneidensis reduces least 86.5% of the in absence direct contact. Biofilm formation accompanies Fe-bead and is observable both macro- microscopically. catalyzed by live cells adapted anaerobic conditions, maximal rates require sustained protein synthesis. The amount reactive ferric system available excess such that...

Summary Although it has long been known that microbes can generate energy using diverse strategies, only recently become clear a growing number involve electron transfer to or from extracellular substrates. The best‐known example of what we will term ‘extracellular respiration’ is between and minerals, such as iron manganese (hydr)oxides. This makes sense, given these minerals are sparingly soluble. What perhaps surprising, however, substrates might typically be classified ‘soluble’ also...

Shewanella species are renowned for their respiratory versatility, including ability to respire poorly soluble substrates by using enzymatic machinery that is localized the outside of cell. The engage in “extracellular respiration” date has focused primarily on respiration minerals. Here, we identify two gene clusters oneidensis strain MR-1 each contain homologs genes required metal reduction and predicted encode dimethyl sulfoxide (DMSO) reductase subunits. Molecular genetic analyses these...

Cellular metabolism is a series of tightly linked oxidations and reductions that must be balanced. Recycling intracellular electron carriers during fermentation often requires substrate conversion to undesired products, while respiration demands constant addition acceptors. The use electrode-based acceptors balance biotransformations may overcome these constraints. To test this hypothesis, the metal-reducing bacterium Shewanella oneidensis was engineered stoichiometrically convert glycerol...

While typically investigated as a microorganism capable of extracellular electron transfer to minerals or anodes, Shewanella oneidensis MR-1 can also facilitate flow from cathode terminal acceptors, such fumarate oxygen, thereby providing model system for process that has significant environmental and technological implications. This work demonstrates cathodic electrons enter the transport chain S. when oxygen is used acceptor. The effect inhibitors suggested proton gradient generated during...

Although several reports have documented nitric oxide (NO) regulation of biofilm formation, the molecular basis this phenomenon is unknown. In many bacteria, an H-NOX (heme-nitric oxide/oxygen-binding) gene found near a diguanylate cyclase (DGC) gene. domains are conserved hemoproteins that known NO sensors. It widely recognized cyclic di-GMP (c-di-GMP) ubiquitous bacterial signaling molecule regulates transition between motility and biofilm. Therefore, may influence formation through DGC,...

Shewanella oneidensis strain MR-1 is a facultative anaerobic bacterium capable of respiring multitude electron acceptors, many which require the Mtr respiratory pathway. The core pathway includes periplasmic c-type cytochrome (MtrA), an integral outer-membrane β-barrel protein (MtrB), and outer-membrane-anchored (MtrC). Together, these components facilitate transfer electrons from CymA in cytoplasmic membrane to acceptors at beyond outer-membrane. genes encoding proteins have paralogs S....

Fe(II)-oxidizing aerobic bacteria are poorly understood, due in part to the difficulties involved laboratory cultivation. Specific challenges include (i) providing a steady supply of electrons as Fe(II) while (ii) managing rapid formation insoluble Fe(III) oxide precipitates and (iii) maintaining oxygen concentrations micromolar range minimize abiotic oxidation. Electrochemical approaches offer an opportunity study that require problematic electron donors or acceptors their respiration. In...

Significance Electricity-producing bacteria are potential power sources, fermentation platforms, and desalination systems, if current densities could be increased. These organisms form conductive biofilms on electrodes, allowing new cell layers to contribute production until a limit is reached, but the biological underpinning of this not well-understood. We investigated limitation behind phenomenon using stable isotope probing nanoscale secondary ion mass spectrometry, showing active cells...

Some bacteria and archaea have evolved the means to use extracellular electron donors acceptors for energy metabolism, a phenomenon broadly known as transfer (EET). One such EET mechanism is transmembrane conduit MtrCAB, which has been shown electrons derived from metabolic substrates acceptors, like Fe(III) Mn(IV) oxides, outside cell. Although most studies of MtrCAB-mediated conducted in Shewanella oneidensis MR-1, recent investigations Vibrio Aeromonas species revealed that...

Base excision repair (BER) enzymes maintain the integrity of genome, and in humans, BER mutations are associated with cancer. Given remarkable sensitivity DNA-mediated charge transport (CT) to mismatched damaged base pairs, we have proposed that DNA glycosylases (EndoIII MutY) containing a redox-active [4Fe4S] cluster could use CT signaling one another search cooperatively for damage genome. Here, examine this model, where estimate electron transfers over few hundred pairs sufficient rapid...