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

这项工作在财政上得到了资助, 为特别促进研究从日本促进科学学会 (jsp) KAKENHI 授予数字 24000010, 17H04969 和 JP17J02602, 美国海军研究全球办公室 (N62909-17-1-2038)。Y.T. 是一个 jsp 研究研究员, 并通过该项目的领导研究生学校 (功绩) 支持的 jsp。

1. 在 ITO 电极上形成oneidensis MR-1 的单层生物膜 (图 1)
注: 为了防止电化学反应器与其他微生物的污染, 电化学反应器的所有介质、装置和元件应预先消毒。当使用oneidensis MR-1 单元格并构造电化学反应器时, 所有程序都应在干净的工作台上进行。
<ol><li>oneidensis MR-1 细胞的培养 注: 在以前报告的4的条件下, 在 ITO 电极...

<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. Sci. 2 (5), 506-516 (2009).</li><li>Okamoto, A., Nakamura, R., 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=In-vivo+identification+of+direct+electron+transfer+from+Shewanella+oneidensis+MR-1+to+electrodes+via+outer-membrane+OmcA-MtrCAB+protein+complexes.">In-vivo identification of direct electron transfer from Shewanella oneidensis MR-1 to electrodes via outer-membrane OmcA-MtrCAB protein complexes.</a> Electrochim. Acta. 56 (16), 5526-5531 (2011).</li><li>Strycharz, S. 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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. 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与蛋白质电化学相比, 我们的全细胞电化学检测具有多种技术优势。蛋白质纯化需要多步骤的耗时程序, 但我们的全细胞方法在细胞培养后需要一天的自组织生物膜形成。为了实现 OM c-青旅和电极之间的稳定交互, 我们只需要对电极表面进行杀菌和清洗;它不需要电极修改来组织蛋白质的方向4,例如, S. oneidensis MR-1 本质上附着在电极上, 同时将 OM c-青旅定?...

在一个完整的细菌细胞中, 直接表征氧化还原蛋白的电化学技术最近出现, 自从发现了金属还原微生物菌株, 如S. oneidensis MR-1 或地杆菌能 sulfurreducens PCA,其中有外膜 c 型细胞色素复合体 (OM c-青旅) 暴露于细胞外部1,2,3,4,5。OM c-青旅介导从呼吸道链到位于 extracellularly 的固体基底的电子传输。此传输称为胞外电子传输 (EET)1,6 , 是新兴生物技术 (如微生物燃料电池6) 的关键过程。因此, 为了了解潜在的 EET 动力学和机制, 以及它与微生物生理学的联系, OM c-中青旅已使用全细胞电化学47, 结合显微术进行了研究。8,9, 光谱学10,11, 分子生物学2,4。相比之下, 研究 EET 相关的阳离子传输 (例如,质子) 对活细胞中 EET 动力学的影响的方法几乎没有建立, 尽管质子在细菌膜中的转运具有关键作用, 在信号、稳态和能源生产12,13,14。在本研究中, 我们描述了一个技术, 以检查质子传输对 EET 动力学的影响, 在S. oneidensis MR-1 细胞使用全细胞电化学测量, 这需要确定的速率限制步骤在微生物电流生产15。
一个直接的方法来评估质子传输对相关 EET 的贡献是氘动能同位素效应 (绢)。绢是可观察的作为电子转移动力学的变化在替换质子与氘离子, 代表质子传输对电子转移动力学的影响16。绢本身的理论已得到很好的建立使用电化学测量与纯化酶17。但是, 由于oneidensis中的当前生产 MR-1 来自多个、不同和波动的进程18, 因此不能简单地将 EET 标识为速率限制过程。为了观察质子传输过程与 EET 耦合的绢, 我们需要确认微生物电流的产生是通过 OM c-中青旅对电极的电子传输来限制的。为此, 在绢测量前, 我们在最佳 pH 值和温度条件下, 用含有高浓度乳酸的新鲜培养基取代上清液;这个替换服务两个角色: (1) 它提高了上游代谢过程的速率与 EET 相比, (2) 省略了在工作电极上从S. oneidensis MR-1 的单层生物膜上释放的上清液中的游泳细胞 (铟锡掺杂氧化物 (ITO) 电极)。所提供的详细协议旨在帮助新的从业者保持并确认 EET 过程是速率确定步骤。

<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

在细菌外膜中嵌入的c型细胞色素复合物的直接电化学检测 (外膜c型细胞色素复合物;OM c-青旅) 最近出现作为一种新的全细胞分析方法来表征细菌电子运输从呼吸道链到细胞外部, 称为细胞外电子转运 (EET)。研究了 EET 反应过程中电子流的途径和动力学, 研究了与 EET 相关的阳离子输送的影响的全细胞电化学方法尚未建立。在本研究中, 本文介绍了通过 OM c-中青旅使用模型微生物 (希瓦氏菌 oneidensis MR-1) 检测 EET 上氘动力学同位素效应 (绢) 的生物化学技术的例子。如果 EET 通过 OM c-青旅作为微生物电流生产中的速率限制步骤, 则可以获得 EET 过程的绢。为此, 在添加 D2O 之前, 将上清液替换为含有足够数量的电子捐献者的新鲜介质, 以支持上游代谢反应的速率, 并从统一的浮游细胞中移除工作电极上的单层生物膜。此外, 还介绍了通过 OM c-青旅法确定微生物电流生产中 EET 速率限制步骤的替代方法。研究质子转运动力学的全细胞电化学检测技术可应用于其它活性微生物菌株。

25 h 的潜在应用在 +0.4 V (对她), 在 ITO 玻璃的工作电极上形成单层生物膜, 以前是通过扫描电子显微镜或共聚焦显微镜4确认的。在单层生物膜形成过程中, 从oneidensis MR-1 的当前生产的代表性时间过程显示在图 2中。尽管电流在每次测量中都有改变, 但如果单层生物膜均匀形成, 则产生的电流不会从图 2中的?...

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

电化学检测氘动力学同位素对希瓦氏菌 oneidensis MR-1 细胞外电子传输的影响

在这里, 我们提出了一个全细胞电化学实验的协议, 以研究质子传输的贡献, 通过外膜细胞色素复合体在希瓦氏菌 oneidensis MR-1 的细胞外电子转运率。

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

核小体的重建与差异同位素标记的姐妹组蛋白

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

科研

生物化学

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

时间分辨电喷雾电离氢氘交换质谱用于研究蛋白质结构与动态

Intrinsically disordered proteins (IDPs) have long been a challenge to structural biologists due to their lack of stable secondary structure elements. ...

Analyzing Supercomplexes of the Mitochondrial Electron Transport Chain with Native Electrophoresis, In-gel Assays, and Electroelution

用天然电泳，凝胶电泳和电解法分析线粒体电子传递链的超复合物

The mitochondrial electron transport chain (ETC) transduces the energy derived from the breakdown of various fuels into the bioenergetic currency of the ...

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

细菌显示文库的半自动化筛选肽亲和试剂的发现与分离结果分析

Biopanning bacterial display libraries is a proven technique for peptide affinity reagent discovery for recognition of both biotic and abiotic targets. ...

A Simple Method for High Throughput Chemical Screening in Caenorhabditis Elegans

A Simple Method for High Throughput Chemical Screening in Caenorhabditis Elegans

一种简单的高通量化学筛选方法在秀丽线虫中的应用

Caenorhabditis elegans is a useful organism for testing chemical effects on physiology. Whole organism small molecule screens offer significant advantages ...

Measuring Trans-Plasma Membrane Electron Transport by C2C12 Myotubes

C2C12 Myotubes 测量反式等离子体膜电子传输

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

用氢-氘交换质谱法定义 Hsp33's 氧化还原调节陪护活动和 Hsp33 映射构象变化

Living organisms regularly need to cope with fluctuating environments during their life cycle, including changes in temperature, pH, the accumulation of ...

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

用于稳定碳氧同位素分析的牙釉质碳酸盐的取样与预处理

Stable carbon and oxygen isotope analysis of human and animal tooth enamel carbonate has been applied in paleodietary, paleoecological, and ...

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

低亲和力受体-配体相互作用的细胞外蛋白微阵列技术

Secreted factors, membrane-tethered receptors, and their interacting partners are main regulators of cellular communication and initiation of signaling ...

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

β-淀粉脂质诱导纤维蛋白斑点结构异常的光谱分析

This article presents methods for generating in vitro fibrin clots and analyzing the effect of beta-amyloid (A&#946;) protein on clot formation and ...