Sulfur in humin as a redox-active element for extracellular electron transfer

Geoderma ◽  
2022 ◽  
Vol 408 ◽  
pp. 115580
Author(s):  
Duyen Minh Pham ◽  
Hiroshi Oji ◽  
Shinya Yagi ◽  
Satoshi Ogawa ◽  
Arata Katayama
Keyword(s):  
Electron Transfer ◽  
Active Element ◽  
Extracellular Electron Transfer ◽  
Redox Active

scholarly journals Molecular design of cytocompatible amphiphilic redox-active polymers for efficient extracellular electron transfer

2017 ◽  
Vol 114 ◽  
pp. 8-12 ◽  
Author(s):  
Masahiro Kaneko ◽  
Masahito Ishikawa ◽  
Kazuhito Hashimoto ◽  
Shuji Nakanishi
Keyword(s):  
Electron Transfer ◽  
Molecular Design ◽  
Extracellular Electron Transfer ◽  
Redox Active

scholarly journals Geothrix fermentans Secretes Two Different Redox-Active Compounds To Utilize Electron Acceptors across a Wide Range of Redox Potentials

2012 ◽  
Vol 78 (19) ◽  
pp. 6987-6995 ◽  
Author(s):  
Misha G. Mehta-Kolte ◽  
Daniel R. Bond
Keyword(s):  
Electron Transfer ◽  
Redox Potential ◽  
Electron Acceptor ◽  
Extracellular Electron Transfer ◽  
Redox Potentials ◽  
Active Compounds ◽  
Content Type ◽  
Electron Shuttles ◽  
Redox Active ◽  
Geothrix Fermentans

ABSTRACTThe current understanding of dissimilatory metal reduction is based primarily on isolates from the proteobacterial generaGeobacterandShewanella. However, environments undergoing active Fe(III) reduction often harbor less-well-studied phyla that are equally abundant. In this work, electrochemical techniques were used to analyze respiratory electron transfer by the only known Fe(III)-reducing representative of theAcidobacteria,Geothrix fermentans. In contrast to previously characterized metal-reducing bacteria, which typically reach maximal rates of respiration at electron acceptor potentials of 0 V versus standard hydrogen electrode (SHE),G. fermentansrequired potentials as high as 0.55 V to respire at its maximum rate. In addition,G. fermentanssecreted two different soluble redox-active electron shuttles with separate redox potentials (−0.2 V and 0.3 V). The compound with the lower midpoint potential, responsible for 20 to 30% of electron transfer activity, was riboflavin. The behavior of the higher-potential compound was consistent with hydrophilic UV-fluorescent molecules previously found inG. fermentanssupernatants. Both electron shuttles were also produced when cultures were grown with Fe(III), but not when fumarate was the electron acceptor. This study reveals thatGeothrixis able to take advantage of higher-redox-potential environments, demonstrates that secretion of flavin-based shuttles is not confined toShewanella, and points to the existence of high-potential-redox-active compounds involved in extracellular electron transfer. Based on differences between the respiratory strategies ofGeothrixandGeobacter, these two groups of bacteria could exist in distinctive environmental niches defined by redox potential.

scholarly journals Microbial electroactive biofilms dominated by Geoalkalibacter spp. from a highly saline–alkaline environment

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Sukrampal Yadav ◽  
Sunil A. Patil
Keyword(s):  
Electron Transfer ◽  
Amplicon Sequencing ◽  
Extracellular Electron Transfer ◽  
Microbial Electrochemistry ◽  
16S Rrna Amplicon Sequencing ◽  
Redox Active ◽  
Lonar Lake ◽  
Current Densities ◽  
The Mean

Abstract Understanding of the extreme microorganisms that possess extracellular electron transfer (EET) capabilities is pivotal to advance electromicrobiology discipline and to develop niche-specific microbial electrochemistry-driven biotechnologies. Here, we report on the microbial electroactive biofilms (EABs) possessing the outward EET capabilities from a haloalkaline environment of the Lonar lake. We used the electrochemical cultivation approach to enrich haloalkaliphilic EABs under 9.5 pH and 20 g/L salinity conditions. The electrodes controlled at 0.2 V vs. Ag/AgCl yielded the best-performing biofilms in terms of maximum bioelectrocatalytic current densities of 548 ± 23 and 437 ± 17 µA/cm2 with acetate and lactate substrates, respectively. Electrochemical characterization of biofilms revealed the presence of two putative redox-active moieties with the mean formal potentials of 0.183 and 0.333 V vs. Ag/AgCl, which represent the highest values reported to date for the EABs. 16S-rRNA amplicon sequencing of EABs revealed the dominance of unknown Geoalkalibacter sp. at ~80% abundance. Further investigations on the haloalkaliphilic EABs possessing EET components with high formal potentials might offer interesting research prospects in electromicrobiology.

scholarly journals Extracellular DNA promotes efficient extracellular electron transfer by pyocyanin in Pseudomonas aeruginosa biofilms

2019 ◽  
Author(s):  
Scott H. Saunders ◽  
Edmund C.M. Tse ◽  
Matthew D. Yates ◽  
Fernanda Jiménez Otero ◽  
Scott A. Trammell ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Electron Transfer ◽  
Redox Reactions ◽  
Extracellular Dna ◽  
Extracellular Electron Transfer ◽  
Bacterial Biofilms ◽  
Active Metabolites ◽  
Electron Shuttles ◽  
Redox Active

SUMMARYExtracellular electron transfer (EET), the process whereby cells access electron acceptors or donors that reside many cell lengths away, enables metabolic activity by microorganisms, particularly under oxidant-limited conditions that occur in multicellular bacterial biofilms. Although different mechanisms underpin this process in select organisms, a widespread strategy involves extracellular electron shuttles, redox-active metabolites that are secreted and recycled by diverse bacteria. How these shuttles catalyze electron transfer within biofilms without being lost to the environment has been a long-standing question. Here, we show that phenazine electron shuttles mediate efficient EET through interactions with extracellular DNA (eDNA) in Pseudomonas aeruginosa biofilms, which are important in nature and disease. Retention of pyocyanin (PYO) and phenazine carboxamide in the biofilm matrix is facilitated by binding to eDNA. In vitro, different phenazines can exchange electrons in the presence or absence of DNA and phenazines can participate directly in redox reactions through DNA; the biofilm eDNA can also support rapid electron transfer between redox active intercalators. Electrochemical measurements of biofilms indicate that retained PYO supports an efficient redox cycle with rapid EET and slow loss from the biofilm. Together, these results establish that eDNA facilitates phenazine metabolic processes in P. aeruginosa biofilms, suggesting a model for how extracellular electron shuttles achieve retention and efficient EET in biofilms.

scholarly journals Improper Localization of the OmcS Cytochrome May Explain the Inability of thexapD-Deficient Mutant ofGeobacter sulfurreducensto Reduce Fe(III) Oxide

2017 ◽  
Author(s):  
Kelly A. Flanagan ◽  
Ching Leang ◽  
Joy E. Ward ◽  
Derek R. Lovley
Keyword(s):  
Electron Transfer ◽  
Electron Transport ◽  
Type Strain ◽  
Wild Type Strain ◽  
Geobacter Sulfurreducens ◽  
Extracellular Electron Transfer ◽  
Outer Cell ◽  
Wild Type ◽  
Redox Active ◽  
In The Wild

AbstractExtracellular electron transfer through a redox-active exopolysaccharide matrix has been proposed as a strategy for extracellular electron transfer to Fe(III) oxide byGeobacter sulfurreducens,based on the phenotype of axapD-deficient strain. Central to this model was the assertion that thexapD-deficient strain produced pili decorated with the multi-hemec-type cytochrome OmcS in manner similar to the wild-type strain. Further examination of thexapD-deficient strain with immunogold labeling of OmcS and transmission electron microscopy revealed that OmcS was associated with the outer cell surface rather than pili. PilA, the pilus monomer, could not be detected in thexapD-deficient strain under conditions in which it was readily detected in the wild-type strain. Multiple lines of evidence in previous studies have suggested that long-range electron transport to Fe(III) oxides proceeds through electrically conductive pili and that OmcS associated with the pili is necessary for electron transfer from the pili to Fe(III) oxides. Therefore, an alternative explanation for the Fe(III) oxide reduction phenotype of thexapD-deficientstrain is that the pili-OmcS route for extracellular electron transport to Fe(III) oxide has been disrupted in thexapD-deficient strain.

Extracellular Electron Transfer across Bacterial Cell Membranes via a Cytocompatible Redox-Active Polymer

ChemPhysChem ◽  
2013 ◽  
Vol 14 (10) ◽  
pp. 2159-2163 ◽  
Author(s):  
Koichi Nishio ◽  
Ryuhei Nakamura ◽  
Xiaojie Lin ◽  
Tomohiro Konno ◽  
Kazuhiko Ishihara ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Bacterial Cell ◽  
Cell Membranes ◽  
Extracellular Electron Transfer ◽  
Redox Active
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