scholarly journals Anodes Stimulate Anaerobic Toluene Degradation via Sulfur Cycling in Marine Sediments

2015 ◽  
Vol 82 (1) ◽  
pp. 297-307 ◽  
Author(s):  
Matteo Daghio ◽  
Eleni Vaiopoulou ◽  
Sunil A. Patil ◽  
Ana Suárez-Suárez ◽  
Ian M. Head ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Marine Sediments ◽  
Sulfur Metabolism ◽  
Direct Electron Transfer ◽  
Rrna Gene ◽  
Toluene Degradation ◽  
Α Subunit ◽  
Mediated Electron Transfer ◽  
Benzylsuccinate Synthase ◽  
Pcr Targeting

ABSTRACTHydrocarbons released during oil spills are persistent in marine sediments due to the absence of suitable electron acceptors below the oxic zone. Here, we investigated an alternative bioremediation strategy to remove toluene, a model monoaromatic hydrocarbon, using a bioanode. Bioelectrochemical reactors were inoculated with sediment collected from a hydrocarbon-contaminated marine site, and anodes were polarized at 0 mV and +300 mV (versus an Ag/AgCl [3 M KCl] reference electrode). The degradation of toluene was directly linked to current generation of up to 301 mA m−2and 431 mA m−2for the bioanodes polarized at 0 mV and +300 mV, respectively. Peak currents decreased over time even after periodic spiking with toluene. The monitoring of sulfate concentrations during bioelectrochemical experiments suggested that sulfur metabolism was involved in toluene degradation at bioanodes. 16S rRNA gene-based Illumina sequencing of the bulk anolyte and anode samples revealed enrichment with electrocatalytically active microorganisms, toluene degraders, and sulfate-reducing microorganisms. Quantitative PCR targeting the α-subunit of the dissimilatory sulfite reductase (encoded bydsrA) and the α-subunit of the benzylsuccinate synthase (encoded bybssA) confirmed these findings. In particular, members of the familyDesulfobulbaceaewere enriched concomitantly with current production and toluene degradation. Based on these observations, we propose two mechanisms for bioelectrochemical toluene degradation: (i) direct electron transfer to the anode and/or (ii) sulfide-mediated electron transfer.

scholarly journals X-ray structure of the direct electron transfer-type FAD glucose dehydrogenase catalytic subunit complexed with a hitchhiker protein

2019 ◽  
Vol 75 (9) ◽  
pp. 841-851 ◽  
Author(s):  
Hiromi Yoshida ◽  
Katsuhiro Kojima ◽  
Masaki Shiota ◽  
Keiichi Yoshimatsu ◽  
Tomohiko Yamazaki ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Disulfide Bonds ◽  
Hydrophobic Interactions ◽  
Direct Electron Transfer ◽  
Glucose Dehydrogenase ◽  
Catalytic Subunit ◽  
Effective Electron ◽  
Α Subunit ◽  
X Ray ◽  
Membrane Bound

The bacterial flavin adenine dinucleotide (FAD)-dependent glucose dehydrogenase complex derived from Burkholderia cepacia (BcGDH) is a representative molecule of direct electron transfer-type FAD-dependent dehydrogenase complexes. In this study, the X-ray structure of BcGDHγα, the catalytic subunit (α-subunit) of BcGDH complexed with a hitchhiker protein (γ-subunit), was determined. The most prominent feature of this enzyme is the presence of the 3Fe–4S cluster, which is located at the surface of the catalytic subunit and functions in intramolecular and intermolecular electron transfer from FAD to the electron-transfer subunit. The structure of the complex revealed that these two molecules are connected through disulfide bonds and hydrophobic interactions, and that the formation of disulfide bonds is required to stabilize the catalytic subunit. The structure of the complex revealed the putative position of the electron-transfer subunit. A comparison of the structures of BcGDHγα and membrane-bound fumarate reductases suggested that the whole BcGDH complex, which also includes the membrane-bound β-subunit containing three heme c moieties, may form a similar overall structure to fumarate reductases, thus accomplishing effective electron transfer.

scholarly journals Comparison of Direct and Mediated Electron Transfer for Bilirubin Oxidase from Myrothecium Verrucaria. Effects of Inhibitors and Temperature on the Oxygen Reduction Reaction

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1056 ◽  
Author(s):  
Riccarda Antiochia ◽  
Diego Oyarzun ◽  
Julio Sánchez ◽  
Federico Tasca
Keyword(s):  
Electron Transfer ◽  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Direct Electron Transfer ◽  
Reduction Reaction ◽  
Redox Mediator ◽  
Bilirubin Oxidase ◽  
Myrothecium Verrucaria ◽  
Physiological Conditions ◽  
Mediated Electron Transfer

One of the processes most studied in bioenergetic systems in recent years is the oxygen reduction reaction (ORR). An important challenge in bioelectrochemistry is to achieve this reaction under physiological conditions. In this study, we used bilirubin oxidase (BOD) from Myrothecium verrucaria, a subclass of multicopper oxidases (MCOs), to catalyse the ORR to water via four electrons in physiological conditions. The active site of BOD, the T2/T3 cluster, contains three Cu atoms classified as T2, T3α, and T3β depending on their spectroscopic characteristics. A fourth Cu atom; the T1 cluster acts as a relay of electrons to the T2/T3 cluster. Graphite electrodes were modified with BOD and the direct electron transfer (DET) to the enzyme, and the mediated electron transfer (MET) using an osmium polymer (OsP) as a redox mediator, were compared. As a result, an alternative resting (AR) form was observed in the catalytic cycle of BOD. In the absence and presence of the redox mediator, the AR direct reduction occurs through the trinuclear site (TNC) via T1, specifically activated at low potentials in which T2 and T3α of the TNC are reduced and T3β is oxidized. A comparative study between the DET and MET was conducted at various pH and temperatures, considering the influence of inhibitors like H2O2, F−, and Cl−. In the presence of H2O2 and F−, these bind to the TNC in a non-competitive reversible inhibition of O2. Instead; Cl− acts as a competitive inhibitor for the electron donor substrate and binds to the T1 site.

scholarly journals NADPH performs mediated electron transfer in cyanobacterial-driven bio-photoelectrochemical cells

iScience ◽  
2021 ◽  
Vol 24 (1) ◽  
pp. 101892
Author(s):  
Yaniv Shlosberg ◽  
Benjamin Eichenbaum ◽  
Tünde N. Tóth ◽  
Guy Levin ◽  
Varda Liveanu ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Photoelectrochemical Cells ◽  
Mediated Electron Transfer

scholarly journals On the role of non-diagonal system–environment interactions in bridge-mediated electron transfer

2020 ◽  
Vol 153 (18) ◽  
pp. 185101
Author(s):  
Nirmalendu Acharyya ◽  
Roman Ovcharenko ◽  
Benjamin P. Fingerhut
Keyword(s):  
Electron Transfer ◽  
System Environment ◽  
Diagonal System ◽  
Mediated Electron Transfer

scholarly journals Amperometric Biosensors Based on Direct Electron Transfer Enzymes

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4525
Author(s):  
Franziska Schachinger ◽  
Hucheng Chang ◽  
Stefan Scheiblbrandner ◽  
Roland Ludwig
Keyword(s):  
Electron Transfer ◽  
Electrode Materials ◽  
Direct Electron Transfer ◽  
Accurate Determination ◽  
Direct Electrochemistry ◽  
Product Analysis ◽  
Amperometric Biosensors ◽  
Chemical Surface ◽  
Fusion Enzymes ◽  
Cost Efficient

The accurate determination of analyte concentrations with selective, fast, and robust methods is the key for process control, product analysis, environmental compliance, and medical applications. Enzyme-based biosensors meet these requirements to a high degree and can be operated with simple, cost efficient, and easy to use devices. This review focuses on enzymes capable of direct electron transfer (DET) to electrodes and also the electrode materials which can enable or enhance the DET type bioelectrocatalysis. It presents amperometric biosensors for the quantification of important medical, technical, and environmental analytes and it carves out the requirements for enzymes and electrode materials in DET-based third generation biosensors. This review critically surveys enzymes and biosensors for which DET has been reported. Single- or multi-cofactor enzymes featuring copper centers, hemes, FAD, FMN, or PQQ as prosthetic groups as well as fusion enzymes are presented. Nanomaterials, nanostructured electrodes, chemical surface modifications, and protein immobilization strategies are reviewed for their ability to support direct electrochemistry of enzymes. The combination of both biosensor elements—enzymes and electrodes—is evaluated by comparison of substrate specificity, current density, sensitivity, and the range of detection.

scholarly journals Characterization and Transcriptome Analysis of a Long-Chain n-Alkane-Degrading Strain Acinetobacter Pittii SW-1

2021 ◽  
Vol 18 (12) ◽  
pp. 6365
Author(s):  
Weina Kong ◽  
Cheng Zhao ◽  
Xingwang Gao ◽  
Liping Wang ◽  
Qianqian Tian ◽  
...  
Keyword(s):  
Unsaturated Fatty Acids ◽  
Sulfur Metabolism ◽  
Quantitative Polymerase Chain Reaction ◽  
Deep Ocean ◽  
Rrna Gene ◽  
Alkane Hydroxylase ◽  
Degradation Rates ◽  
Acinetobacter Pittii ◽  
Ocean Environment ◽  
Long Chain

Strain sw-1, isolated from 7619-m seawater of the Mariana Trench, was identified as Acinetobacter pittii by 16S rRNA gene and whole-genome sequencing. A. pittii sw-1 was able to efficiently utilize long-chain n-alkanes (C18–C36), but not short- and medium-chain n-alkanes (C8–C16). The degradation rate of C20 was 91.25%, followed by C18, C22, C24, C32, and C36 with the degradation rates of 89.30%, 84.03%, 80.29%, 30.29%, and 13.37%, respectively. To investigate the degradation mechanisms of n-alkanes for this strain, the genome and the transcriptome analyses were performed. Four key alkane hydroxylase genes (alkB, almA, ladA1, and ladA2) were identified in the genome. Transcriptomes of strain sw-1 grown in C20 or CH3COONa (NaAc) as the sole carbon source were compared. The transcriptional levels of alkB and almA, respectively, increased 78.28- and 3.51-fold in C20 compared with NaAc, while ladA1 and ladA2 did not show obvious change. The expression levels of other genes involved in the synthesis of unsaturated fatty acids, permeases, membrane proteins, and sulfur metabolism were also upregulated, and they might be involved in n-alkane uptake. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) confirmed that alkB expression was significantly induced by C20, C24, and C32, and almA induction extent by C24 and C32 was higher than that with C20. Furthermore, ladA2 expression was only induced by C32, and ladA1 expression was not induced by any of n-alkanes. In addition, A. pittii sw-1 could grow with 0%–3% NaCl or 8 out of 10 kinds of the tested heavy metals and degrade n-alkanes at 15 °C. Taken together, these results provide comprehensive insights into the degradation of long-chain n-alkanes by Acinetobacter isolated from the deep ocean environment.

scholarly journals Enhancement of Direct Electron Transfer in Graphene Bioelectrodes Containing Novel Cytochrome c Variants with Optimized Heme Orientation

2021 ◽  
pp. 107818
Author(s):  
Miriam Izzo ◽  
Silvio Osella ◽  
Margot Jacquet ◽  
Małgorzata Kiliszek ◽  
Ersan Harputlu ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Cytochrome C ◽  
Direct Electron Transfer
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