Methanogenesis from methyl-CoM and H2, as catalyzed by inside-out vesicle preparations of the methanogenenic bacterium strain Gö1, was associated with ATP synthesis. That this ATP synthesis proceeded via an uncoupler-sensitive transmembrane proton gradient was concluded from the following results:
- 1Various inhibitors that affected methane formation (e.g. 2-bromomethanesulfonate) also prevented ATP synthesis.
- 2The protonophore 3,5-di-tert-butyl-4-hydroxybenzylidenemalononitrile, in combination with the K+ ionophore valinomycin, inhibited ATP synthesis completely without affecting methanogenesis.
- 3The ATP synthase inhibitor diethylstilbestrol inhibited ATP synthesis.
- 4Addition of the detergent sulfobetaine inhibited both methane formation and ATP synthesis; the former but not the latter could be restored by adding titanium(III) citrate as electron donor.
In addition it was shown that ATP synthesis could also be driven by transmembrane proton gradients artificially imposed on the vesicles. Furthermore net methanogenesis-dependent ATP formation was shown by measuring [32P]phosphate incorporation.