Extracellular electron transfer features of Gram-positive bacteria

Pankratova, Galina; Hederstedt, Lars; Gorton, Lo

doi:10.1016/j.aca.2019.05.007

Cited by 137 publications

(90 citation statements)

References 253 publications

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“…In contrast to Gram‐negative organisms, such as Shewanella and Geobacter , Gram‐positive bacteria are characterized by possessing a cell wall composed of peptidoglycan, sugars, phospholipids, peptides, amino acids, and glycoprotein . It was proposed that the thick peptidoglycan layer would prevent Gram‐positive bacteria from performing extracellular electron transfer . However, the isolation of Thermincola potens strain JR in a current‐producing MFC operating at high temperature altered this view .…”

Section: The Cell‐surface Cytochromes Of Gram‐positive Bacteriamentioning

confidence: 99%

Role of multiheme cytochromes involved in extracellular anaerobic respiration in bacteria

et al. 2019

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Heme containing proteins are involved in a broad range of cellular functions, from oxygen sensing and transport to catalyzing oxidoreductive reactions. The two major types of cytochrome (b‐type and c‐type) only differ in their mechanism of heme attachment, but this has major implications for their cellular roles in both localization and mechanism. The b‐type cytochromes are commonly cytoplasmic, or are within the cytoplasmic membrane, while c‐type cytochromes are always found outside of the cytoplasm. The mechanism of heme attachment allows for complex c‐type multiheme complexes, having the capacity to hold multiple electrons, to be assembled. These are increasingly being identified as secreted into the extracellular environment. For organisms that respire using extracellular substrates, these large multiheme cytochromes allow for electron transfer networks from the cytoplasmic membrane to the cell exterior for the reduction of extracellular electron acceptors. In this review the structures and functions of these networks and the mechanisms by which electrons are transferred to extracellular substrates is described.

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Section: The Cell‐surface Cytochromes Of Gram‐positive Bacteriamentioning

confidence: 99%

Role of multiheme cytochromes involved in extracellular anaerobic respiration in bacteria

et al. 2019

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“…We have demonstrated that DMK is essential for EET and that cytochrome bd activity attenuates EET efficiency in E. faecalis (4). Effective electron transfer from the bacterial cell to an electrode requires a mediatoreither a highly flexible redox polymer that forms a hydrogel together with the bacterial cells and precipitates onto the electrode surface, i.e., osmium-containing redox polymer ([Os(2,2′-bipyridine)2poly(N-vinylimidazole) 10Cl]2+/+) (OsRP), or an added diffusible compound such as ferricyanide (1,3,4). E. faecalis and several other Enterococcus species can reduce exogenous ferric ions (13)(14)(15)(16).…”

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confidence: 99%

Two Routes for Extracellular Electron Transfer in Enterococcus faecalis

2020

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Enterococcus faecalis cells are known to have ferric reductase activity and the ability to transfer electrons generated in metabolism to the external environment. We have isolated mutants defective in ferric reductase activity and studied their electron transfer properties to electrodes mediated by ferric ions and an osmium complex-modified redox polymer (OsRP). Electron transfer mediated with ferric ions and ferric reductase activity were both found to be dependent on the membrane-associated Ndh3 and EetA proteins, consistent with findings in Listeria monocytogenes. In contrast, electron transfer mediated with OsRP was independent of these two proteins. Quinone in the cell membrane was required for the electron transfer with both mediators. The combined results demonstrate that extracellular electron transfer from reduced quinone to ferric ions and to OsRP occurs via different routes in the cell envelope of E. faecalis. IMPORTANCE The transfer of reducing power in the form of electrons, generated in the catabolism of nutrients, from a bacterium to an extracellular acceptor appears to be common in nature. The electron acceptor can be another cell or abiotic material. Such extracellular electron transfer contributes to syntrophic metabolism and is of wide environmental, industrial, and medical importance. Electron transfer between microorganisms and electrodes is fundamental in microbial fuel cells for energy production and for electricity-driven synthesis of chemical compounds in cells. In contrast to the much-studied extracellular electron transfer mediated by cell surface exposed cytochromes, little is known about components and mechanisms for such electron transfer in organisms without these cytochromes and in Gram-positive bacteria such as E. faecalis, which is a commensal gut lactic acid bacterium and opportunistic pathogen.

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“…[ 24 , 25 ]. C. matruchotii is a Gram-positive bacterium, Gram-positive bacteria usually possesses a thick electron non-conductive cell wall and are known to show weak EET capability in many cases [ 26 , 27 ]. However, as the accumulation of reductive energy suppresses fermentation metabolism in pathogens [ 28 ], EET may be an important strategy for them to gain energy for enhancing their colonization and survival by controlling cellular homeostasis.…”

Section: Discussionmentioning

confidence: 99%

Metabolic Current Production by an Oral Biofilm Pathogen Corynebacterium matruchotii

2020

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The development of a simple and direct assay for quantifying microbial metabolic activity is important for identifying antibiotic drugs. Current production capabilities of environmental bacteria via the process called extracellular electron transport (EET) from the cell interior to the exterior is well investigated in mineral-reducing bacteria and have been used for various energy and environmental applications. Recently, the capability of human pathogens for producing current has been identified in different human niches, which was suggested to be applicable for drug assessment, because the current production of a few strains correlated with metabolic activity. Herein, we report another strain, a highly abundant pathogen in human oral polymicrobial biofilm, Corynebacterium matruchotii, to have the current production capability associated with its metabolic activity. It showed the current production of 50 nA/cm2 at OD600 of 0.1 with the working electrode poised at +0.4 V vs. a standard hydrogen electrode in a three-electrode system. The addition of antibiotics that suppress the microbial metabolic activity showed a significant current decrease (>90%), establishing that current production reflected the cellular activity in this pathogen. Further, the metabolic fixation of atomically labeled 13C (31.68% ± 2.26%) and 15N (19.69% ± 1.41%) confirmed by high-resolution mass spectrometry indicated that C. matruchotii cells were metabolically active on the electrode surface. The identified electrochemical activity of C. matruchotii shows that this can be a simple and effective test for evaluating the impact of antibacterial compounds, and such a method might be applicable to the polymicrobial oral biofilm on electrode surfaces, given four other oral pathogens have already been shown the current production capability.

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Extracellular electron transfer features of Gram-positive bacteria

Cited by 137 publications

References 253 publications

Role of multiheme cytochromes involved in extracellular anaerobic respiration in bacteria

Role of multiheme cytochromes involved in extracellular anaerobic respiration in bacteria

Two Routes for Extracellular Electron Transfer in Enterococcus faecalis

Metabolic Current Production by an Oral Biofilm Pathogen Corynebacterium matruchotii

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