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  • Hydrogenase-independent uptake and metabolism of electrons by the archaeon Methanococcus maripaludis.

Hydrogenase-independent uptake and metabolism of electrons by the archaeon Methanococcus maripaludis.

The ISME journal (2014-05-23)
Svenja T Lohner, Jörg S Deutzmann, Bruce E Logan, John Leigh, Alfred M Spormann
ABSTRACT

Direct, shuttle-free uptake of extracellular, cathode-derived electrons has been postulated as a novel mechanism of electron metabolism in some prokaryotes that may also be involved in syntrophic electron transport between two microorganisms. Experimental proof for direct uptake of cathodic electrons has been mostly indirect and has been based on the absence of detectable concentrations of molecular hydrogen. However, hydrogen can be formed as a transient intermediate abiotically at low cathodic potentials (<-414 mV) under conditions of electromethanogenesis. Here we provide genetic evidence for hydrogen-independent uptake of extracellular electrons. Methane formation from cathodic electrons was observed in a wild-type strain of the methanogenic archaeon Methanococcus maripaludis as well as in a hydrogenase-deletion mutant lacking all catabolic hydrogenases, indicating the presence of a hydrogenase-independent mechanism of electron catabolism. In addition, we discovered a new route for hydrogen or formate production from cathodic electrons: Upon chemical inhibition of methanogenesis with 2-bromo-ethane sulfonate, hydrogen or formate accumulated in the bioelectrochemical cells instead of methane. These results have implications for our understanding on the diversity of microbial electron uptake and metabolism.

MATERIALS
Product Number
Brand
Product Description

Supelco
Activated Charcoal Norit®, Norit® RBAA-3, rod
Sigma-Aldrich
Methane-12C, 13C-depleted, 99.9 atom % 12C
Sigma-Aldrich
Carbon nanofibers, graphitized, platelets(conical), >98% carbon basis, D × L 100 nm × 20-200 μm
Sigma-Aldrich
Carbon nanofibers, pyrolitically stripped, platelets(conical), >98% carbon basis, D × L 100 nm × 20-200 μm
Carbon - Vitreous, rod, 50mm, diameter 1.0mm, glassy carbon
Carbon - Vitreous, rod, 100mm, diameter 5.0mm, glassy carbon
Carbon - Vitreous, foil, 100x100mm, thickness 6.0mm, glassy carbon
Carbon - Vitreous, foil, 10x10mm, thickness 4.0mm, glassy carbon
Carbon - Vitreous, rod, 100mm, diameter 1.0mm, glassy carbon
Carbon - Vitreous, rod, 5mm, diameter 3.0mm, glassy carbon
Carbon - Vitreous, foil, 25x25mm, thickness 0.5mm, glassy carbon
Carbon - Vitreous, rod, 100mm, diameter 3.0mm, glassy carbon
Carbon - Vitreous, tube, 100mm, outside diameter 10mm, inside diameter 3mm, wall thickness 3.5mm, glassy carbon
Carbon - Vitreous, rod, 200mm, diameter 10mm, glassy carbon
Carbon - Vitreous, foam, 150x150mm, thickness 2.5mm, bulk density 0.05g/cm3, porosity 96.5%
Carbon - Vitreous, foam, 150x150mm, 0.05g.cmué, porosity 96.5%, 24 pores/cm
Carbon - Vitreous, tube, 50mm, outside diameter 10mm, inside diameter 3mm, wall thickness 3.5mm, glassy carbon
Carbon - Vitreous, foam, 300x300mm, thickness 20mm, bulk density 0.05g/cm3, porosity 96.5%
Carbon - Vitreous, rod, 100mm, diameter 7.0mm, glassy carbon
Carbon - Vitreous, foil, 100x100mm, thickness 1.0mm, glassy carbon
Carbon - Vitreous, foil, 25x25mm, thickness 4.0mm, glassy carbon
Carbon - Vitreous, foil, 100x100mm, thickness 2.0mm, glassy carbon
Carbon - Vitreous, foil, 8x8mm, thickness 0.5mm, glassy carbon
Carbon - Vitreous, foil, 50x50mm, thickness 4.0mm, glassy carbon
Carbon - Vitreous, rod, 200mm, diameter 1.0mm, glassy carbon
Carbon - Vitreous, foam, 150x150mm, thickness 3.2mm, bulk density 0.05g/cm3, porosity 96.5%
Carbon - Vitreous, foam, 300x300mm, thickness 30mm, bulk density 0.05g/cm3, porosity 96.5%
Carbon - Vitreous, rod, 200mm, diameter 5.0mm, glassy carbon
Carbon - Vitreous, foil, 50x50mm, thickness 1.0mm, glassy carbon
Carbon - Vitreous, rod, 200mm, diameter 3.0mm, glassy carbon