Electrochemically-active microorganisms (EAM) are relevant to metal biogeochemistry and have appl... more Electrochemically-active microorganisms (EAM) are relevant to metal biogeochemistry and have applications in microbial fuel cells (MFCs), bioremediation, and bioelectrocatalysis. Most research conducted to date focuses on EAM hailing from two distinct genera, namely Shewanella and Geobacter, with a relatively limited number of EAM discovered in recent years. This review article summarises current approaches to novel EAM enrichment, in terms of inoculum choice, growth medium, reactor configuration, electrochemical characterisation and community profiling through metagenomics and metatranscriptomics. A novel roadmap for EAM enrichment and subsequent characterisation using environmental samples as a starting material is provided in order to increase throughput and hence the likelihood of discovering novel EAM.
Chemical communications (Cambridge, England), Jan 4, 2015
In Pseudomonas aeruginosa, chemical deconvolution of the pyocyanin voltammetric signal allows its... more In Pseudomonas aeruginosa, chemical deconvolution of the pyocyanin voltammetric signal allows its expression to be observed simultaneously with the quorum sensing molecule Pseudomonas quinolone signal (PQS). Such analysis has revealed that PQS might protect pyocyanin from self-oxidation, but also exert a pro-oxidative effect on pyocyanin under oxidative conditions to produce additional redox metabolites.
The mechanism by which extracellular metabolites including redox mediators and quorum sensing sig... more The mechanism by which extracellular metabolites including redox mediators and quorum sensing signaling molecules, traffic through the extracellular matrix of biofilms is poorly explored. We hypothesize that functional amyloids, abundant in natural biofilms and possessing hydrophobic domains, retain these metabolites. Using surface plasmon resonance, we demonstrate that the quorum sensing (QS) molecules, 2-heptyl-3,4- dihydroxyquinoline (PQS) and N-(3- oxododecanoyl)-L-homoserine lactone (3-oxo- C12-HSL), and the redox mediator pyocyanin bind with transient affinity to functional amyloids from Pseudomonas (Fap). Their high hydrophobicity predisposes them to signal- amyloid interactions, but specific interactions also play a role. Transient interactions allow for rapid association and dissociation kinetics, which make the QS molecules bioavailable and at the same time secure within the extracellular matrix as a consequence of serial bindings. Retention of the QS molecules was confirm...
Joseph Anthony Menicucci Jr. 1, Haluk Beyenal 1, Enrico Marsili 2, Raaja Raajan Angathevar Veluch... more Joseph Anthony Menicucci Jr. 1, Haluk Beyenal 1, Enrico Marsili 2, Raaja Raajan Angathevar Veluchamy 1, Goksel Demir 3, and Zbigniew Lewandowski 4.(1) Department of Chemical and Biological Engineering, Montana State University-Bozeman, 366 EPS ...
Electrochemical Methods for Observing Electron Transfer from Bacterial Biofilms to Conductive Sur... more Electrochemical Methods for Observing Electron Transfer from Bacterial Biofilms to Conductive Surfaces. [ECS Meeting Abstracts 701, 454 (2007)]. Enrico Marsili, Daniel Bond.
Electroactive biofilms are capable of extracellular electron transfer to insoluble metal oxides a... more Electroactive biofilms are capable of extracellular electron transfer to insoluble metal oxides and electrodes; such biofilms are relevant to biogeochemistry, bioremediation, and bioelectricity production. We investigated the extracellular electron transfer mechanisms in Shewanella loihica PV-4 viable biofilms grown at indium tin oxide (ITO) and graphite electrodes in potentiostat-controlled electrochemical cells poised at 0.2 V vs. Ag/AgCl. Chronoamperometry and confocal microscopy showed higher biofilm growth at graphite compared to the ITO electrode. Cyclic voltammetry, differential pulse voltammetry, along with fluorescence spectroscopy showed that direct electron transfer through outer membrane c type cytochromes (Omcs) prevailed at the biofilm/ITO interface, while biofilms formed at graphite electrode reduced the electrode also via secreted redox mediators, such as flavins and quinones. The biofilm age does not affect the prevalent transfer mechanism at ITO electrodes. On the ...
Electrochemically-active microorganisms (EAM) are relevant to metal biogeochemistry and have appl... more Electrochemically-active microorganisms (EAM) are relevant to metal biogeochemistry and have applications in microbial fuel cells (MFCs), bioremediation, and bioelectrocatalysis. Most research conducted to date focuses on EAM hailing from two distinct genera, namely Shewanella and Geobacter, with a relatively limited number of EAM discovered in recent years. This review article summarises current approaches to novel EAM enrichment, in terms of inoculum choice, growth medium, reactor configuration, electrochemical characterisation and community profiling through metagenomics and metatranscriptomics. A novel roadmap for EAM enrichment and subsequent characterisation using environmental samples as a starting material is provided in order to increase throughput and hence the likelihood of discovering novel EAM.
Chemical communications (Cambridge, England), Jan 4, 2015
In Pseudomonas aeruginosa, chemical deconvolution of the pyocyanin voltammetric signal allows its... more In Pseudomonas aeruginosa, chemical deconvolution of the pyocyanin voltammetric signal allows its expression to be observed simultaneously with the quorum sensing molecule Pseudomonas quinolone signal (PQS). Such analysis has revealed that PQS might protect pyocyanin from self-oxidation, but also exert a pro-oxidative effect on pyocyanin under oxidative conditions to produce additional redox metabolites.
The mechanism by which extracellular metabolites including redox mediators and quorum sensing sig... more The mechanism by which extracellular metabolites including redox mediators and quorum sensing signaling molecules, traffic through the extracellular matrix of biofilms is poorly explored. We hypothesize that functional amyloids, abundant in natural biofilms and possessing hydrophobic domains, retain these metabolites. Using surface plasmon resonance, we demonstrate that the quorum sensing (QS) molecules, 2-heptyl-3,4- dihydroxyquinoline (PQS) and N-(3- oxododecanoyl)-L-homoserine lactone (3-oxo- C12-HSL), and the redox mediator pyocyanin bind with transient affinity to functional amyloids from Pseudomonas (Fap). Their high hydrophobicity predisposes them to signal- amyloid interactions, but specific interactions also play a role. Transient interactions allow for rapid association and dissociation kinetics, which make the QS molecules bioavailable and at the same time secure within the extracellular matrix as a consequence of serial bindings. Retention of the QS molecules was confirm...
Joseph Anthony Menicucci Jr. 1, Haluk Beyenal 1, Enrico Marsili 2, Raaja Raajan Angathevar Veluch... more Joseph Anthony Menicucci Jr. 1, Haluk Beyenal 1, Enrico Marsili 2, Raaja Raajan Angathevar Veluchamy 1, Goksel Demir 3, and Zbigniew Lewandowski 4.(1) Department of Chemical and Biological Engineering, Montana State University-Bozeman, 366 EPS ...
Electrochemical Methods for Observing Electron Transfer from Bacterial Biofilms to Conductive Sur... more Electrochemical Methods for Observing Electron Transfer from Bacterial Biofilms to Conductive Surfaces. [ECS Meeting Abstracts 701, 454 (2007)]. Enrico Marsili, Daniel Bond.
Electroactive biofilms are capable of extracellular electron transfer to insoluble metal oxides a... more Electroactive biofilms are capable of extracellular electron transfer to insoluble metal oxides and electrodes; such biofilms are relevant to biogeochemistry, bioremediation, and bioelectricity production. We investigated the extracellular electron transfer mechanisms in Shewanella loihica PV-4 viable biofilms grown at indium tin oxide (ITO) and graphite electrodes in potentiostat-controlled electrochemical cells poised at 0.2 V vs. Ag/AgCl. Chronoamperometry and confocal microscopy showed higher biofilm growth at graphite compared to the ITO electrode. Cyclic voltammetry, differential pulse voltammetry, along with fluorescence spectroscopy showed that direct electron transfer through outer membrane c type cytochromes (Omcs) prevailed at the biofilm/ITO interface, while biofilms formed at graphite electrode reduced the electrode also via secreted redox mediators, such as flavins and quinones. The biofilm age does not affect the prevalent transfer mechanism at ITO electrodes. On the ...
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