Axial Ligation of Heme in c-Type Cytochromes of LivingShewanella oneidensis: A New Insight into Enhanced Extracellular Electron Transfer

2015 ◽  
Vol 2 (11) ◽  
pp. 1672-1677 ◽  
Author(s):  
Yong Yuan ◽  
Laicai Li ◽  
Shungui Zhou
Keyword(s):  
Electron Transfer ◽  
Extracellular Electron Transfer ◽  
Axial Ligation ◽  
Insight Into

scholarly journals Metatranscriptomics Supports the Mechanism for Biocathode Electroautotrophy by “Candidatus Tenderia electrophaga”

mSystems ◽  
2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Brian J. Eddie ◽  
Zheng Wang ◽  
W. Judson Hervey ◽  
Dagmar H. Leary ◽  
Anthony P. Malanoski ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Direct Electron Transfer ◽  
Electron Donors ◽  
Extracellular Electron Transfer ◽  
Uncultured Bacterium ◽  
Microbial Electrosynthesis ◽  
Electrode Cell ◽  
Electron Transfer Processes ◽  
New Evidence ◽  
Insight Into

ABSTRACT Bacteria that directly use electrodes as metabolic electron donors (biocathodes) have been proposed for applications ranging from microbial electrosynthesis to advanced bioelectronics for cellular communication with machines. However, just as we understand very little about oxidation of analogous natural insoluble electron donors, such as iron oxide, the organisms and extracellular electron transfer (EET) pathways underlying the electrode-cell direct electron transfer processes are almost completely unknown. Biocathodes are a stable biofilm cultivation platform to interrogate both the rate and mechanism of EET using electrochemistry and to study the electroautotrophic organisms that catalyze these reactions. Here we provide new evidence supporting the hypothesis that the uncultured bacterium “Candidatus Tenderia electrophaga” directly couples extracellular electron transfer to CO2 fixation. Our results provide insight into developing biocathode technology, such as microbial electrosynthesis, as well as advancing our understanding of chemolithoautotrophy. Biocathodes provide a stable electron source to drive reduction reactions in electrotrophic microbial electrochemical systems. Electroautotrophic biocathode communities may be more robust than monocultures in environmentally relevant settings, but some members are not easily cultivated outside the electrode environment. We previously used metagenomics and metaproteomics to propose a pathway for coupling extracellular electron transfer (EET) to carbon fixation in “Candidatus Tenderia electrophaga,” an uncultivated but dominant member of an electroautotrophic biocathode community. Here we validate and refine this proposed pathway using metatranscriptomics of replicate aerobic biocathodes poised at the growth potential level of 310 mV and the suboptimal 470 mV (versus the standard hydrogen electrode). At both potentials, transcripts were more abundant from “Ca. Tenderia electrophaga” than from any other constituent, and its relative activity was positively correlated with current. Several genes encoding key components of the proposed “Ca. Tenderia electrophaga” EET pathway were more highly expressed at 470 mV, consistent with a need for cells to acquire more electrons to obtain the same amount of energy as at 310 mV. These included cyc2, encoding a homolog of a protein known to be involved in iron oxidation. Mean expression of all CO2 fixation-related genes is 0.27 log2-fold higher at 310 mV, indicating that reduced energy availability at 470 mV decreased CO2 fixation. Our results substantiate the claim that “Ca. Tenderia electrophaga” is the key electroautotroph, which will help guide further development of this community for microbial electrosynthesis. IMPORTANCE Bacteria that directly use electrodes as metabolic electron donors (biocathodes) have been proposed for applications ranging from microbial electrosynthesis to advanced bioelectronics for cellular communication with machines. However, just as we understand very little about oxidation of analogous natural insoluble electron donors, such as iron oxide, the organisms and extracellular electron transfer (EET) pathways underlying the electrode-cell direct electron transfer processes are almost completely unknown. Biocathodes are a stable biofilm cultivation platform to interrogate both the rate and mechanism of EET using electrochemistry and to study the electroautotrophic organisms that catalyze these reactions. Here we provide new evidence supporting the hypothesis that the uncultured bacterium “Candidatus Tenderia electrophaga” directly couples extracellular electron transfer to CO2 fixation. Our results provide insight into developing biocathode technology, such as microbial electrosynthesis, as well as advancing our understanding of chemolithoautotrophy.

scholarly journals Modeling biofilms with dual extracellular electron transfer mechanisms

2013 ◽  
Vol 15 (44) ◽  
pp. 19262 ◽  
Author(s):  
Ryan Renslow ◽  
Jerome Babauta ◽  
Andrew Kuprat ◽  
Jim Schenk ◽  
Cornelius Ivory ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Extracellular Electron Transfer ◽  
Transfer Mechanisms

scholarly journals Using Structure-Function Relationships to Understand the Mechanism of Phenazine Mediated Extracellular Electron Transfer in Escherichia coli

iScience ◽  
2021 ◽  
pp. 103033
Author(s):  
Zayn Rhodes ◽  
Olja Simoska ◽  
Ashwini Dantanarayana ◽  
Keith J. Stevenson ◽  
Shelley D. Minteer
Keyword(s):  
Escherichia Coli ◽  
Electron Transfer ◽  
Structure Function ◽  
Extracellular Electron Transfer

scholarly journals Ecophysiology of Freshwater Verrucomicrobia Inferred from Metagenome-Assembled Genomes

mSphere ◽  
2017 ◽  
Vol 2 (5) ◽  
Author(s):  
Shaomei He ◽  
Sarah L. R. Stevens ◽  
Leong-Keat Chan ◽  
Stefan Bertilsson ◽  
Tijana Glavina del Rio ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Potential Role ◽  
Carbon Sources ◽  
Genomic Analysis ◽  
Distribution Patterns ◽  
Eutrophic Lake ◽  
Genomic Diversity ◽  
Extracellular Electron Transfer ◽  
Different Origins ◽  
Encoding Genes

ABSTRACT Freshwater Verrucomicrobia spp. are cosmopolitan in lakes and rivers, and yet their roles and ecophysiology are not well understood, as cultured freshwater Verrucomicrobia spp. are restricted to one subdivision of this phylum. Here, we greatly expanded the known genomic diversity of this freshwater lineage by recovering 19 Verrucomicrobia draft genomes from 184 metagenomes collected from a eutrophic lake and a humic bog across multiple years. Most of these genomes represent the first freshwater representatives of several Verrucomicrobia subdivisions. Genomic analysis revealed Verrucomicrobia to be potential (poly)saccharide degraders and suggested their adaptation to carbon sources of different origins in the two contrasting ecosystems. We identified putative extracellular electron transfer genes and so-called “Planctomycete-specific” cytochrome c-encoding genes and identified their distinct distribution patterns between the lakes/layers. Overall, our analysis greatly advances the understanding of the function, ecophysiology, and distribution of freshwater Verrucomicrobia, while highlighting their potential role in freshwater carbon cycling. Microbes are critical in carbon and nutrient cycling in freshwater ecosystems. Members of the Verrucomicrobia are ubiquitous in such systems, and yet their roles and ecophysiology are not well understood. In this study, we recovered 19 Verrucomicrobia draft genomes by sequencing 184 time-series metagenomes from a eutrophic lake and a humic bog that differ in carbon source and nutrient availabilities. These genomes span four of the seven previously defined Verrucomicrobia subdivisions and greatly expand knowledge of the genomic diversity of freshwater Verrucomicrobia. Genome analysis revealed their potential role as (poly)saccharide degraders in freshwater, uncovered interesting genomic features for this lifestyle, and suggested their adaptation to nutrient availabilities in their environments. Verrucomicrobia populations differ significantly between the two lakes in glycoside hydrolase gene abundance and functional profiles, reflecting the autochthonous and terrestrially derived allochthonous carbon sources of the two ecosystems, respectively. Interestingly, a number of genomes recovered from the bog contained gene clusters that potentially encode a novel porin-multiheme cytochrome c complex and might be involved in extracellular electron transfer in the anoxic humus-rich environment. Notably, most epilimnion genomes have large numbers of so-called “Planctomycete-specific” cytochrome c-encoding genes, which exhibited distribution patterns nearly opposite to those seen with glycoside hydrolase genes, probably associated with the different levels of environmental oxygen availability and carbohydrate complexity between lakes/layers. Overall, the recovered genomes represent a major step toward understanding the role, ecophysiology, and distribution of Verrucomicrobia in freshwater. IMPORTANCE Freshwater Verrucomicrobia spp. are cosmopolitan in lakes and rivers, and yet their roles and ecophysiology are not well understood, as cultured freshwater Verrucomicrobia spp. are restricted to one subdivision of this phylum. Here, we greatly expanded the known genomic diversity of this freshwater lineage by recovering 19 Verrucomicrobia draft genomes from 184 metagenomes collected from a eutrophic lake and a humic bog across multiple years. Most of these genomes represent the first freshwater representatives of several Verrucomicrobia subdivisions. Genomic analysis revealed Verrucomicrobia to be potential (poly)saccharide degraders and suggested their adaptation to carbon sources of different origins in the two contrasting ecosystems. We identified putative extracellular electron transfer genes and so-called “Planctomycete-specific” cytochrome c-encoding genes and identified their distinct distribution patterns between the lakes/layers. Overall, our analysis greatly advances the understanding of the function, ecophysiology, and distribution of freshwater Verrucomicrobia, while highlighting their potential role in freshwater carbon cycling.

Geobacter sulfurreducens adapts to low electrode potential for extracellular electron transfer

2016 ◽  
Vol 191 ◽  
pp. 743-749 ◽  
Author(s):  
Luo Peng ◽  
Xiao-Ting Zhang ◽  
Jie Yin ◽  
Shuo-Yuan Xu ◽  
Yong Zhang ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Electrode Potential ◽  
Geobacter Sulfurreducens ◽  
Extracellular Electron Transfer
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