Mode of sodium ion action on methanogenesis and ATPase of the moderate halophilic methanogenis bacterium Methanohalophilus halophilus

[摘要]

Cells of Methanohalophilus halophilus swelled when exposed to hypotonic solutions of NaCl at pH 7.0. The swelling of the cells ceased in the presence of Mg²⁺. Methane formation by non-growing cells was strongly dependent on the NaCl concentration. Among other monovalent and divalent cations only Li⁺ and Mg²⁺ could partly substitute for a specific function of sodium ions. The artificial Na⁺/H⁺ antiporter, monensin, exerted a strong inhibitory effect on methane formation from methylamine. The membrane-bound Mg²⁺-stimulated ATPase of these cells was enhanced at low (40 mM) NaCl concentration while higher concentrations of this solute were inhibitory. The results obtained show that sodium ions are a prerequisite for optimal methane formation and ATPase activity in these cells. However, both of these processes required different sodium ion concentrations.

[学科分类] 生物化学/生物物理

[关键词] Halophilic methanogen;Sodium ion;Methanogenesis;ATPase;Methanohalophilus halophilus