メタン生成菌における膜成分依存的なメチル-CoMからのメタン生成：ホルムアルデヒドおよび分子状水素を電子供与体として
Methanogenesis from methyl-CoM and H2 by the soluble fraction of the methanogenic bacterium strain Göl was enhanced up to tenfold upon addition of a membrane fraction. This enhancement was reproducible with membranes derived from phylogenetically diverse methanogenic species, but absent when membranes from Escherichia coli or Acetobacterium woodii were used. Irreversible loss of stimulatory activity occurred following exposure to strong oxidants (O2, K3[Fe(CN)6]) or SH-reactive reagents (Ag+, p-chloromercuribenzoate, iodoacetamide), as well as heat treatment above 78°C. When formaldehyde replaced H2 as the electron donor, membrane dependence was similarly observed: in the presence of membranes, 1 mol HCHO was oxidized to CO2 with concomitant production of 2 mol CH4 from methyl-CoM. Without membranes, only 1 mol H2 and 1 mol CH4 were produced per mol HCHO at 10–20% of the membrane-supported rate. Substitution of methyl-CoM with an artificial acceptor system (methylviologen/metronidazole) abolished membrane-dependent stimulation of formaldehyde oxidation. These findings provide the first direct evidence that membrane components are essential for electron transfer during methanogenesis.
Membrane components of methanogenic bacteria are essential for electron transfer during methyl-CoM-dependent methanogenesis. Oxidation of membrane constituents or modification of thiol groups irreversibly abolishes stimulatory activity, indicating redox-sensitive membrane proteins mediate H2 or formaldehyde-coupled methane production.
This is basic research at the cellular or molecular level. For human application, inhalation is the most promising delivery route, but inhalation carries explosion risk and concentration matters (empirical LFL of 10%; high-concentration devices are not recommended).
See also:
https://h2-papers.org/en/papers/2513188