Name: electrochemical detection of deuterium kinetic isotope effect on extracellular electron transport in shewanella oneidensis mr-1
Uploaded: 2018-04-16T14:30:00
Description: Watch this Scientific Journal Video about Electrochemical Detection of Deuterium Kinetic Isotope Effect on Extracellular Electron Transport in Shewanella oneidensis MR-1 at JoVE.com

Este trabalho é apoiado financeiramente por um subsídio para investigação especialmente promovido da sociedade para a promoção da ciência (JSPS) número de concessão KAKENHI 24000010, 17H 04969, Japão e JP17J02602, nos escritório do Naval Research Global (N62909-17-1-2038). Y.T. é um pesquisador de JSPS e apoiado por JSPS através do programa para liderar graduação escolas (mérito).

1. formação de um biofilme monocamada de S. oneidensis MR-1 em um eletrodo de ITO (Figura 1)
Nota: Para evitar a contaminação do reator eletroquímico com outros micróbios, toda a mídia, Implementos e componentes do reator eletroquímico devem ser esterilizadas com antecedência. Quando usando células S. oneidensis MR-1 e construir os reatores eletroquímicos, devem efectuar-se todos os procedimentos em uma bancada limpa.
<ol><li>Cultivo...

<ol>
	<li>Nealson, K. H., Saffarini, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Iron+and+Manganese+in+Anaerobic+Respiration+-+Environmental+Significance,+Physiology,+and+Regulation.">Iron and Manganese in Anaerobic Respiration - Environmental Significance, Physiology, and Regulation.</a> Annu. Rev. Microbiol. 48, 311-343 (1994).</li><li>Bretschger, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Current+production+and+metal+oxide+reduction+by+Shewanella+oneidensis+MR-1+wild+type+and+mutants.">Current production and metal oxide reduction by Shewanella oneidensis MR-1 wild type and mutants.</a> Appl Environ Microb. 73 (21), 7003-7012 (2007).</li><li>Richter, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cyclic+voltammetry+of+biofilms+of+wild+type+and+mutant+Geobacter+sulfurreducens+on+fuel+cell+anodes+indicates+possible+roles+of+OmcB,+OmcZ,+type+IV+pili,+and+protons+in+extracellular+electron+transfer.">Cyclic voltammetry of biofilms of wild type and mutant Geobacter sulfurreducens on fuel cell anodes indicates possible roles of OmcB, OmcZ, type IV pili, and protons in extracellular electron transfer.</a> Energy Environ. 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Jpn. 88 (5), 690-692 (2015).</li><li>Okamoto, A., Tokunou, Y., Saito, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cation-limited+kinetic+model+for+microbial+extracellular+electron+transport+via+an+outer+membrane+cytochrome+C+complex.">Cation-limited kinetic model for microbial extracellular electron transport via an outer membrane cytochrome C complex.</a> Biophysics and physicobiology. 13, 71-76 (2016).</li><li>Okamoto, A., Tokunou, Y., Shafeer, K., Hashimoto, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proton+Transport+in+the+Outer-Membrane+Flavocytochrome+Complex+Limits+the+Rate+of+Extracellular+Electron+Transport.">Proton Transport in the Outer-Membrane Flavocytochrome Complex Limits the Rate of Extracellular Electron Transport.</a> Angew. Chem. Int. Ed. 56, 9082-9086 (2017).</li><li>Hammes-Schiffer, S., Stuchebrukhov, A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Theory+of+Coupled+Electron+and+Proton+Transfer+Reactions.">Theory of Coupled Electron and Proton Transfer Reactions.</a> Chem. Rev. 110 (12), 6939-6960 (2010).</li><li>Cleland, W. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+isotope+effects+to+determine+enzyme+mechanisms.">The use of isotope effects to determine enzyme mechanisms.</a> J Biol. Chem. 278 (52), 51975-51984 (2003).</li><li>Kouzuma, A., Kasai, T., Hirose, A., Watanabe, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Catabolic+and+regulatory+systems+in+Shewanella+oneidensis+MR-1+involved+in+electricity+generation+in+microbial+fuel+cells.">Catabolic and regulatory systems in Shewanella oneidensis MR-1 involved in electricity generation in microbial fuel cells.</a> Front. Microbiol. 6, (2015).</li><li>Kushner, D. J., Baker, A., Dunstall, T. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pharmacological+uses+and+perspectives+of+heavy+water+and+deuterated+compounds.">Pharmacological uses and perspectives of heavy water and deuterated compounds.</a> Can. J Physiol. Pharm. 77 (2), 79-88 (1999).</li><li>Xie, X. S., Zubarev, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+Low-Level+Deuterium+Enrichment+on+Bacterial+Growth.">Effects of Low-Level Deuterium Enrichment on Bacterial Growth.</a> Plos One. 9 (7), e102071 (2014).</li><li>Okamoto, A., Hashimoto, K., Nealson, K. H., Nakamura, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rate+enhancement+of+bacterial+extracellular+electron+transport+involves+bound+flavin+semiquinones.">Rate enhancement of bacterial extracellular electron transport involves bound flavin semiquinones.</a> Proc. Natl. Acad. Sci. U. S. A. 110 (19), 7856-7861 (2013).</li><li>Edwards, M. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Redox+Linked+Flavin+Sites+in+Extracellular+Decaheme+Proteins+Involved+in+Microbe-Mineral+Electron+Transfer.">Redox Linked Flavin Sites in Extracellular Decaheme Proteins Involved in Microbe-Mineral Electron Transfer.</a> Sci. Rep. 5, 11677 (2015).</li><li>Saito, J., Hashimoto, K., Okamoto, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flavin+as+an+Indicator+of+the+Rate-Limiting+Factor+for+Microbial+Current+Production+in+Shewanella+oneidensis+MR-1.">Flavin as an Indicator of the Rate-Limiting Factor for Microbial Current Production in Shewanella oneidensis MR-1.</a> Electrochim. Acta. 216, 261-265 (2016).</li><li>Guo, J. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduction+of+Cr(VI)+by+Escherichia+coli+BL21+in+the+presence+of+redox+mediators.">Reduction of Cr(VI) by Escherichia coli BL21 in the presence of redox mediators.</a> Bioresource Technol. 123, 713-716 (2012).</li><li>Nealson, K., Saffarini, D., Moser, D., Smith, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Spectrophotometric+Method+for+Monitoring+Tactic+Responses+of+Bacteria+under+Anaerobic+Conditions.">A Spectrophotometric Method for Monitoring Tactic Responses of Bacteria under Anaerobic Conditions.</a> J Microbiol. Meth. 20 (3), 211-218 (1994).</li><li>Myers, C. R., Myers, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+surface+exposure+of+the+outer+membrane+cytochromes+of+Shewanella+oneidensis+MR-1.">Cell surface exposure of the outer membrane cytochromes of Shewanella oneidensis MR-1.</a> Lett. Appl. Microbiol. 37 (3), 254-258 (2003).</li><li>Lower, B. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Antibody+Recognition+Force+Microscopy+Shows+that+Outer+Membrane+Cytochromes+OmcA+and+MtrC+Are+Expressed+on+the+Exterior+Surface+of+Shewanella+oneidensis+MR-1.">Antibody Recognition Force Microscopy Shows that Outer Membrane Cytochromes OmcA and MtrC Are Expressed on the Exterior Surface of Shewanella oneidensis MR-1.</a> Appl. Environ. Microbiol. 75 (9), 2931-2935 (2009).</li><li>Chen, X. X., Ferrigno, R., Yang, J., Whitesides, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Redox+properties+of+cytochrome+c+adsorbed+on+self-assembled+monolayers:+A+probe+for+protein+conformation+and+orientation.">Redox properties of cytochrome c adsorbed on self-assembled monolayers: A probe for protein conformation and orientation.</a> Langmuir. 18 (18), 7009-7015 (2002).</li><li>McMillan, D. G. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+impact+of+enzyme+orientation+and+electrode+topology+on+the+catalytic+activity+of+adsorbed+redox+enzymes.">The impact of enzyme orientation and electrode topology on the catalytic activity of adsorbed redox enzymes.</a> Electrochim. Acta. 110, 79-85 (2013).</li><li>Dinh, H. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Iron+corrosion+by+novel+anaerobic+microorganisms.">Iron corrosion by novel anaerobic microorganisms.</a> Nature. 427 (6977), 829-832 (2004).</li><li>McGlynn, S. E., Chadwick, G. L., Kempes, C. P., Orphan, V. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single+cell+activity+reveals+direct+electron+transfer+in+methanotrophic+consortia.">Single cell activity reveals direct electron transfer in methanotrophic consortia.</a> Nature. 526 (7574), 531-535 (2015).</li><li>Okamoto, A., Nakamura, R., Nealson, K. H., Hashimoto, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bound+Flavin+Model+Suggests+Similar+Electron-Transfer+Mechanisms+in+Shewanella+and+Geobacter.">Bound Flavin Model Suggests Similar Electron-Transfer Mechanisms in Shewanella and Geobacter.</a> Chemelectrochem. 1 (11), 1808-1812 (2014).</li><li>Okamoto, A., Hashimoto, K., Nealson, K. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flavin+Redox+Bifurcation+as+a+Mechanism+for+Controlling+the+Direction+of+Electron+Flow+during+Extracellular+Electron+Transfer.">Flavin Redox Bifurcation as a Mechanism for Controlling the Direction of Electron Flow during Extracellular Electron Transfer.</a> Angew. Chem. Int. Ed. 53 (41), 10988-10991 (2014).</li><li>Tokunou, Y., Hashimoto, K., Okamoto, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acceleration+of+Extracellular+Electron+Transfer+by+Alternative+Redox-Active+Molecules+to+Riboflavin+for+Outer-Membrane+Cytochrome+c+of+Shewanella+oneidensis+MR-1.">Acceleration of Extracellular Electron Transfer by Alternative Redox-Active Molecules to Riboflavin for Outer-Membrane Cytochrome c of Shewanella oneidensis MR-1.</a> J Phys. Chem. C. 120 (29), 16168-16173 (2016).</li><li>Rowe, A. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tracking+electron+uptake+from+a+cathode+into+Shewanella+cells:+implications+for+generating+maintenance+energy+from+solid+substrates.">Tracking electron uptake from a cathode into Shewanella cells: implications for generating maintenance energy from solid substrates.</a> bioRxiv. , 116475 (2017).</li></ol>

Nosso ensaio eletroquímico de célula inteira tem várias vantagens técnicas em comparação com eletroquímica de proteína. Enquanto a purificação de proteínas requer várias etapas procedimentos demorados, nosso método de célula inteira leva um dia de formação de biofilmes auto-organizado após a cultura de células. Para obter uma interacção estável entre OM c- Cyts e o eletrodo, precisamos apenas de esterilização e limpeza da superfície do eletrodo; não exige modificação de eletrodos para ...

Surgiram recentemente Técnicas eletroquímicas para caracterizar diretamente uma proteína redox em uma célula bacteriana intacta desde a descoberta de cepas microbianas redução de metal, como S. oneidensis MR-1 ou Geobacter sulfurreducens PCA, que tem complexos de citocromo c-tipo de membrana externa (c-Cyts OM) expostos à célula exterior1,2,3,4,5. O OM c- Cyts mediar o transporte de elétrons da cadeia respiratória para substratos sólidos localizado extracelularmente. Este transporte é referido como transporte de elétrons extracelular (EET)1,6 e é um processo crítico para biotecnologias emergentes, tais como células de combustível microbianas6. Portanto, para entender a cinética EET subjacente e mecanismos e a sua ligação à fisiologia microbiana, OM c -Cyts foram investigados usando toda a célula eletroquímica4,7, combinado com microscopia 8 , 9, espectroscopia de10,11e biologia molecular2,4. Em contraste, métodos para investigar o impacto do transporte de cátion EET-associados, por exemplo, os prótons, na cinética EET em células vivas foram mal estabelecidos, apesar do transporte de protões através das membranas bacterianas, tendo um papel crítico sinalização, homeostase e energia produção12,13,14. No presente estudo, descrevemos uma técnica para examinar o impacto do transporte de prótons na cinética EET em S. oneidensis MR-1 célula usando medições eletroquímicas célula inteira, que requer a identificação da etapa limitante de produção atual de microbiana15.
Uma maneira direta para avaliar a contribuição do transporte de prótons sobre a EET associado é o efeito de cinética isótopo deutério (KIE). A KIE é observável como a mudança na cinética de transferência de elétrons sobre a substituição de prótons com íons de deutério, que representa o impacto do transporte de prótons na transferência de elétrons cinética16. A teoria de KIE em si bem estabeleceu usando medições eletroquímicas com enzimas purificada17. No entanto, desde que a produção atual em S. oneidensis MR-1 resulta do múltiplo, processos diversos e flutuação18, um não pode simplesmente identificar EET como o processo limitante. Para observar o KIE em processos de transporte de prótons juntamente com EET, precisamos confirmar que a atual produção microbiana é limitada pelo transporte de elétrons através de OM c- Cyts para o eletrodo. Para este efeito, substituímos a solução sobrenadante por meio fresco, que contém uma alta concentração de lactato como doador de elétron no pH ideal e as condições de temperatura antes da medição KIE; Esta substituição serviu dois papéis: (1) reforçada a taxa dos processos metabólicos montante em comparação com a EET e (2) omitido as células de natação no sobrenadante libertado o biofilme monocamada de S. oneidensis MR-1 sobre o trabalho do eléctrodo ( eletrodo de estanho dopado com óxido (ITO) índio). O protocolo detalhado apresentado destina-se a ajudar novos praticantes manter e confirmar que o processo EET é o passo determinante de taxa.

<table>
	<tbody>
		<tr>
			<td>Glass cylinder</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>Custom-made, used as the electrochemical reactor</td>
		</tr>
		<tr>
			<td>PTFE cover and base</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>Custom-made, used as a cover and a foundation of the electrochemical reactor</td>
		</tr>
		<tr>
			<td>Buthyl rubber</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>Custom-made, inserted between each component of electrochemical reactor</td>
		</tr>
		<tr>
			<td>Septa</td>
			<td>GL Science</td>
			<td>3007-16101</td>
			<td>Used as an injection port of electrochemical reactor</td>
		</tr>
		<tr>
			<td>Indium tin-doped oxide (ITO) electrode</td>
			<td>GEOMATEC</td>
			<td>No.0001</td>
			<td>Used as a working electrode, 5&#937;/sq</td>
		</tr>
		<tr>
			<td>Ag/AgCl KCl saturated electrode</td>
			<td>HOKUTO DENKO</td>
			<td>HX-R5</td>
			<td>Used as a reference electrode, &#934;0.30mm</td>
		</tr>
		<tr>
			<td>Platinum wire</td>
			<td>The Nilaco Cooporation</td>
			<td>PT-351325</td>
			<td>Used as a counter electrode</td>
		</tr>
		<tr>
			<td>Luria-Bertani (LB) Broth, Miller</td>
			<td>Becton, Dichkinson and Company</td>
			<td>244620</td>
			<td>Medium for precultivation of S. oneidensis MR-1</td>
		</tr>
		<tr>
			<td>Bacto agar</td>
			<td>Becton, Dichkinson and Company</td>
			<td>214010</td>
			<td></td>
		</tr>
		<tr>
			<td>Anthraquinone-1-sulfonate (&#945;-AQS)</td>
			<td>TCI</td>
			<td>A1428</td>
			<td></td>
		</tr>
		<tr>
			<td>Flavin mononucleotide (FMN)</td>
			<td>Wako</td>
			<td>184-00831</td>
			<td></td>
		</tr>
		<tr>
			<td>NaHCO3</td>
			<td>Wako</td>
			<td>191-01305</td>
			<td>Used for defined medium (DM)</td>
		</tr>
		<tr>
			<td>CaCl2 &#183; 2H2O</td>
			<td>Wako</td>
			<td>031-00435</td>
			<td>Used for DM</td>
		</tr>
		<tr>
			<td>NH4Cl</td>
			<td>Wako</td>
			<td>011-03015</td>
			<td>Used for DM</td>
		</tr>
		<tr>
			<td>MgCl2 &#183; 6H2O</td>
			<td>Wako</td>
			<td>135-00165</td>
			<td>Used for DM</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Wako</td>
			<td>191-01665</td>
			<td>Used for DM</td>
		</tr>
		<tr>
			<td>2-[4-(2-hydroxyethyl)-1-piperazinyl] ethanesulfonic acid (HEPES)</td>
			<td>DOJINDO</td>
			<td>346-08235</td>
			<td>Used for DM</td>
		</tr>
		<tr>
			<td>Sodium Lactate Solution</td>
			<td>Wako</td>
			<td>195-02305</td>
			<td></td>
		</tr>
		<tr>
			<td>Bacto Yeast Extract</td>
			<td>Becton, Dichkinson and Company</td>
			<td>212750</td>
			<td></td>
		</tr>
		<tr>
			<td>Deuterium oxide (D, 99.9%)</td>
			<td>Cambridge Isotope Laboratories, Inc.</td>
			<td>DLM-4-PK</td>
			<td>Additive for kinetic isotope effect experiments</td>
		</tr>
		<tr>
			<td>Incubator</td>
			<td>TOKYO RIKAKIKAI CO. LTD.</td>
			<td>LTI-601SD</td>
			<td>Used for precultivation</td>
		</tr>
		<tr>
			<td>Shaker</td>
			<td>TAITEC</td>
			<td>NR-3</td>
			<td>Used for precultivation</td>
		</tr>
		<tr>
			<td>Autoclave machine</td>
			<td>TOMY SEIKO CO. LTD.</td>
			<td>LSX-500</td>
			<td>Used for sterilization of the electrochemical reactor and the medium</td>
		</tr>
		<tr>
			<td>Clean bench</td>
			<td>SANYO</td>
			<td>MCV-91BNF</td>
			<td>Used to prevent the contamination of the electrochemical reactor and the medium with other microbes</td>
		</tr>
		<tr>
			<td>Centrifuge separator</td>
			<td>Eppendorf</td>
			<td>5430R</td>
			<td>Rotational speed upto 6000&#215;g is required</td>
		</tr>
		<tr>
			<td>Nitrogen gas generator</td>
			<td>Puequ CO. LTD.</td>
			<td>PNTN-2</td>
			<td>Nitrogen gas cylinder can also be used instead of gas generator</td>
		</tr>
		<tr>
			<td>UV-vis spectrometer</td>
			<td>SHIMADZU</td>
			<td>UV-1800</td>
			<td>Used for optimization of cell density</td>
		</tr>
		<tr>
			<td>Potentiostat</td>
			<td>BioLogic</td>
			<td>VMP3</td>
			<td>Used for biofilm formation and kinetic isotope effect experiments</td>
		</tr>
		<tr>
			<td>Thermal water circulator</td>
			<td>AS ONE</td>
			<td>TR-1A</td>
			<td>Used for maintanance of temperature of electrochemcial reactor</td>
		</tr>
		<tr>
			<td>Faraday cage</td>
			<td>HOKUTO DENKO</td>
			<td>HS-201S</td>
			<td>Used for electrochemical experiments</td>
		</tr>
	</tbody>
</table>

electrochemical detection of deuterium kinetic isotope effect on extracellular electron transport in shewanella oneidensis mr-1

Direto de deteção eletroquímica de c-tipo complexos citocromo embutidos na membrana externa bacteriana (membrana externa c-tipo complexos citocromo; OM c- Cyts) tem recentemente emergiu como um método analítico de células inteiras romance para caracterizar o bacteriano transporte de elétrons da cadeia respiratória para o exterior da célula, referido como o transporte de elétrons extracelular (EET). Enquanto o caminho e a cinética do fluxo de elétrons durante a reação de EET têm sido investigados, um método eletroquímico de células inteiras para examinar o impacto do transporte de cátion associado com EET não ainda foi estabelecido. No presente estudo, um exemplo de uma técnica bioquímica para examinar o efeito de cinética isótopo deutério (KIE) sobre EET através de OM c- Cyts usando um micróbio de modelo, Shewanella oneidensis MR-1, é descrita. A KIE sobre o processo EET pode ser obtido se a EET através de OM c- Cyts atua como o passo limitante na produção atual microbiana. Para o efeito, antes da adição de D2O, o sobrenadante foi substituído com mídia fresca contendo uma quantidade suficiente do doador de elétron para suportar a taxa de upstream reações metabólicas e para remover as células planctônicas de um uniforme monocamada biofilme sobre o eletrodo de trabalho. Métodos alternativos para confirmar o limitante passo na produção atual microbiana como EET através de OM c- Cyts também são descritos. Nossa técnica de um ensaio eletroquímico células inteiras para investigar a cinética de transporte de prótons pode ser aplicada a outras cepas microbianas eletroativos.

Após 25 h de potencial aplicação em 0,4 V (contra ela), formou-se um biofilme monocamada sobre o eletrodo de trabalho de vidro de ITO, que anteriormente foi confirmado por uma microscopia eletrônica ou uma microscopia confocal4. O curso de tempo representativa da atual produção do S. oneidensis MR-1 durante a formação de um biofilme monocamada é mostrado na Figura 2. Embora a corrente altera em cada medição, a corre...

Watch this Scientific Journal Video about Electrochemical Detection of Deuterium Kinetic Isotope Effect on Extracellular Electron Transport in Shewanella oneidensis MR-1 at JoVE.com

Electrochemical Detection of Deuterium Kinetic Isotope Effect on Extracellular Electron Transport in Shewanella oneidensis MR-1

Eletroquímico deteção de deutério cinética efeito isotópico no transporte de elétrons extracelular em Shewanella oneidensis MR-1

Aqui nós apresentamos um protocolo de toda a célula eletroquímicos experimentos para estudar a contribuição do transporte de protões para a taxa de transporte de elétrons extracelular através do membrana externa citocromos complexos em Shewanella oneidensis MR-1.

Direct electrochemical detection of c-type cytochrome complexes embedded in the bacterial outer membrane (outer membrane c-type cytochrome complexes; OM ...

The overall goal of this protocol is to observe the contribution of proton transport to the rate of bacterial extracellular electron transport by the detection of the deuterium kinetic isotope effect. Our method reveals the impact of proton transport on the kinetics of extracellular electron transport or EET from bacteria to an electrode via outer membrane c-type cytochromes. Our assay reflects the native proton management in EET because we used living bacteria rather than purified enzyme.However, our challenge was to remove the noises from other cellular processes. The deuterium kinetic isotope effect termed as KIE is one of the best technique to examine the contribution of proton transport on the associated electron transport process. To grow Shewanella MR-1 cells, transfer one colony of the cells grown on an agar plate into 15 milliliters of LB medium.Grow the cells at 30 degrees Celsius for 24 hours in aerobic conditions with shaking at 160 rpm. Centrifuge the cell suspension at 6, 000 times gravity for 10 minutes. Then, resuspend the resultant cell pellet in 15 milliliters of Defined Medium, supplemented with 10 millimolar lactate as the source of carbon and 0.5 grams per liter yeast extract as trace elements for the cells.After further cultivating the cell suspension aerobically at 30 degrees Celsius for 12 hours with shaking at 160 rpm, centrifuge again at 6, 000 times gravity for 10 minutes. Wash the resultant cell pellet twice with DM medium by centrifugation for 10 minutes at 6, 000 times gravity before the electrochemical experiment. To construct a three-electrode electrochemical reactor, put an ITO substrate as the working electrode at the bottom of the reactor.Subsequently, insert a glass cylinder and a polytetrafluoroethylene cover and insert a platinum wire as the counter-electrode. Then, insert a silver chloride electrode into the reactor as the reference electrode. Next, add four milliliters of DM supplemented with 10 millimolar lactate and 0.5 grams per liter yeast extract into the electrochemical reactor.After confirming that there is no leakage from the electrochemical reactor, flow the nitrogen gas into the electrochemical reactor over 20 minutes to maintain anerobic conditions inside the electrochemical reactor. Connect the electrochemical reactor to a potentiostat and apply a positive 0.4 volts to the ITO electrode, keeping the temperature of the electrochemical reactor at 30 degrees Celsius using an external water circulation system. To perform electrochemical cultivation, first adjust the cell density of the suspension to an optical density of 1.43 at 600 nanometers with DM supplemented by 10 millimolar lactate and 0.5 grams per liter yeast extract.Add 0.3 milliliters of the cell suspension into the electrochemical reactor through the injection port using a syringe. The OD 600 in the reactor changes to 0.1. Continue the potential application at positive 0.4 volts to the ITO electrode for 25 hours.Stop the potential application and disconnect the electrochemical reactor from the potentiostat and the water circulation system. Flow the nitrogen gas into a bottle containing DM with 10 millimolar lactate over 20 minutes to remove oxygen from the medium. Now, extremely slowly and gently, remove all the supernatant from inside the electrochemical reactor using a syringe under flowing nitrogen gas.Then, add four milliliters of fresh DM containing 10 millimolar lactate using a syringe. Slant the electrochemical reactor to remove all of the supernatant on the wall of the reactor. Repeat these steps three times in total.Stop the gas flow and connect the electrochemical reactor to the potentiostat again, applying a positive 0.4 volts to the ITO electrode at 303 Kelvin. Confirm that the current production from a monolayer biofilm of Shewanella MR-1 is stable and does not increase rapidly. If the current increases steeply, wait until the current stabilizes with a 5%increase over 10 minutes.Extremely slowly and gently, add 40 microliters of anoxic 50 volume percent D2O into the electrochemical reactor using a syringe such that the concentration is 0.5 volume percent D2O in the reactor. To prevent damage to the biofilm by D20 addition, inject the D2O dropwise. Wait for the current to stabilize and subsequently add the D2O up to 4.4 volume percent to obtain the KIE value, which is the ratio of current production and presence of D2O and H2O.Check the effect of the same volume of H2O addition on the current production. Here, the solid line is the representative result for the microbial current change induced by D2O addition. Addition of D2O sharply decreased the microbial current within 10 seconds, while H20 had almost no current decrease as shown with the dotted line.To confirm that the observed current decrease by D2O is attributable to electron transport through outer membrane cytochromes, a diffusing electron mediator was used. Here addition of 100 micromolar alpha-AQS enhanced the current production by more than five times and the current production remained unaffected by D2O addition. These results indicate that the kinetics of the metabolic reactions are fast enough so that the extracellular electron transfer process is rate-limiting.An alternative method for assessing this is the addition of the flavin molecule into the electrochemical reactor. An instant anodic current increase by flavin addition indicates rate-limitation by the electron transport process via outer membrane cytochromes. After watching this video, you should have a good understanding of how to examine the kinetic isotope effect on the extracellular electron transport process.The most critical point to successfully obtain the kinetic isotope effect is to clarify and confirm the condition where the electron transport through the outer membrane cytochromes limits the rate of current production. In this video, we introduced two methods to confirm this condition, observation of current change by addition of flavin and by addition of diffusing extra mediator, such as alpha-AQS. Once the rate-limitation is confirmed, this system can be used not only for the deuterium experiment but also for the biochemical characterization of outer membrane cytochromes.Furthermore, this protocol could be applicable to examining other electroactive microbes, as long the extracellular electron transport process is rate-limiting. Our methodology provides a basic and general technique to investigate the extracellular electron transport process via outer membrane cytochromes in vivo.

Research

JoVE Journal

Biochemistry

Electrochemical Detection of Deuterium Kinetic Isotope Effect on Extracellular Electron Transport in Shewanella oneidensis MR-1

Reconstitution of Nucleosomes with Differentially Isotope-labeled Sister Histones

Reconstituição de Nucleosomes com Histones irmã diferencialmente Isotope-rotulados

Asymmetrically modified nucleosomes contain the two copies of a histone (sister histones) decorated with distinct sets of Post-translational Modifications ...

Bioquímica

Time-resolved ElectroSpray Ionization Hydrogen-deuterium Exchange Mass Spectrometry for Studying Protein Structure and Dynamics

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Semi-automated Biopanning of Bacterial Display Libraries for Peptide Affinity Reagent Discovery and Analysis of Resulting Isolates

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Measuring Trans-Plasma Membrane Electron Transport by C2C12 Myotubes

Trans-Plasma da membrana, transporte de elétrons por Myotubes de C2C12 de medição

Trans-plasma membrane electron transport (tPMET) plays a role in protection of cells from intracellular reductive stress as well as protection from damage ...

Defining Hsp33's Redox-regulated Chaperone Activity and Mapping Conformational Changes on Hsp33 Using Hydrogen-deuterium Exchange Mass Spectrometry

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Sampling and Pretreatment of Tooth Enamel Carbonate for Stable Carbon and Oxygen Isotope Analysis

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Extracellular Protein Microarray Technology for High Throughput Detection of Low Affinity Receptor-Ligand Interactions

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Analysis of &#946;-Amyloid-induced Abnormalities on Fibrin Clot Structure by Spectroscopy and Scanning Electron Microscopy

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