Methanogen hydrogenotrophic · Electrotroph · N₂ fixer
Methanococcus maripaludis S2
Methanobacteriota · Methanococci · Methanococcaceae
- Methanogen
- Marine
- Halotolerant
- Tier 2
- Contested EET
01 · Identity
Identity
Where this organism sits in the tree of life, how to obtain it, and what a cell looks like.
Lineage
- domainArchaea
- ›phylumMethanobacteriota
- ›classMethanococci
- ›orderMethanococcales
- ›familyMethanococcaceae
- ›genusMethanococcus
- ›speciesMethanococcus maripaludis S2
Culture collections & accessions
- NCBI taxon
- 267377
Cell morphology
Coccus · Archaeal s layer only
- Motile: yes
02 · Electron transfer
Electron transfer
How electrons cross the cell envelope — the property that makes a microbe useful in an electrochemical system.
No extracellular electron-transfer route is curated for this organism yet.
Mechanisms
Direct transfer — detail
- Notes
- Lohner et al. (2014) reported H2-independent cathodic methane production via Hdr-related pathways; later work (Deutzmann et al. 2015) showed much of the current under those conditions is mediated by extracellularly released hydrogenases / formate dehydrogenases that catalyze H2/formate generation at the cathode. Practical implication for kinetic priors: treat as 'mediated' by default.
- Completeness
- Contested
Other
- Cathode electron uptake mechanism
- Contested
03 · Growth envelope
Growth envelope
The conditions this organism tolerates and what it eats and breathes — the operating window for a reactor.
Energy metabolism
Electron donors
- H2
- Formate
- Cathode
Electron acceptors
- CO2
Carbon sources
- CO2
- Formate
Metabolism — detail
- N₂ fixation
- Yes
- Carbon fixation pathway
- Wood ljungdahl
04 · Growth & electron-transfer kinetics
Growth & electron-transfer kinetics
How fast this organism grows and how hard it pushes electrons into an anode, as the corpus reports it, and what those constants imply when you run them.
Kinetic evidence
| Parameter | Median | 10–90 % | n | Source |
|---|---|---|---|---|
| Max. specific growth rate μmax | 0.1 h⁻¹ | 0.05–0.18 | 3 | genus prior · 2 refs |
| Half-saturation constant Ks | 8 mg/L | 1–30 | 1 | genus prior · 2 refs |
| Biomass yield Y | 0.04 g/g | 0.01–0.07 | 2 | genus prior · 2 refs |
| Decay coefficient kd | Not in the corpus yet | |||
| Exchange current density i₀ | Not in the corpus yet | |||
| Transfer coefficient α | Not in the corpus yet | |||
| Tafel slope | Not in the corpus yet | |||
Median of the extracted values, the 10–90 % spread behind it and how many values it pools.
Evidence rows (0)
Genus-level prior: Methanococcus maripaludis
A genus-level prior is a summary for the whole genus, not a measurement on this strain.
Constants that drive the simulation
Scenario — values you set, not evidence
Growth simulation
Scenario: Initial substrate 1000 mg/L · Initial attached biomass 0.1 g/m² · Anode area per liquid volume 100 m²/m³ · Duration 72 h · Batch. Values you set, not evidence.
No current model
The current needs Max. current density jmax, Half-saturation potential E_KA, which this source does not have.
- Substrate-saturated growth
- Slowing
- Stationary
Monod growth has no lag phase; the bands mark where the net growth rate is near its maximum, falling, near zero or negative.
Simulator notes
- decayPerH absent: no endogenous decay term, so growth is an upper bound
- biofilmDensityKgPerM3 absent: thickness not computed (thicknessUm = null)
- no anodePotentialVvsShe / overpotentialV given: current not computed (currentDensityAPerM2 = null)
- substrate floored at 0 on 1 step(s): reduce dtH for a finer exhaustion front
These curves are a Monod and Nernst-Monod idealisation (after Marcus et al. 2007 and Torres et al. 2008), parameterised only by the constants listed above: each one carries its n and its 10–90 % range, and a constant with n = 1 has no spread at all. No diffusion inside the biofilm, no detachment, no coulombic-efficiency split. The scenario values are yours, not evidence.
05 · Performance
Performance
Reported electrochemical output, the role it plays in a reactor, and what it produces.
Role in a reactor
Products (1)
| Product | Max titerg/L | Max rate | Coulombic efficiency |
|---|---|---|---|
| methane | — | — | — |
06 · Ecology & biofilm
Ecology & biofilm
How it lives on an electrode, who it partners with, and where it is found in nature.
Ecosystems
- Marine
- Sediment marine
07 · Applications, engineering & safety
Applications, engineering & safety
Where it has been put to work, how tractable it is to engineer, and what handling it requires.
Applications (1)
- Microbial electrosynthesis methaneTRL 3/9
Biosafety
- Pathogen: no
08 · Sources & data quality
Sources & data quality
Every value above traces to a citation. This is how complete and how confident the record is.
Record quality
Literature reviewed 2026-05-13 · schema v1.3.0 · updated 2026-05-13 · imported 2026-05-13
Open data gaps (2)
- 'Direct' vs hydrogenase-mediated cathode uptake debate unresolved.
- Genetic tractability is excellent but biochemical mapping of EET path incomplete.
References (2)
- Lohner ST, et al. (2014). Hydrogenase-independent uptake and metabolism of electrons by the archaeon Methanococcus maripaludis. ISME J 8:1673-1681.doi:10.1038/ismej.2014.82
- Deutzmann JS, Sahin M, Spormann AM (2015). Extracellular enzymes facilitate electron uptake in biocorrosion and bioelectrosynthesis. mBio 6:e00496-15.doi:10.1128/mBio.00496-15