Methanogenesis is Ca2+ dependent in Methanothermobacter thermautotrophicus strain DeltaH.

Area of Science:

• Microbiology
• Biochemistry
• Archaea Physiology

Background:

• Methanogenesis is a vital biological process.
• The role of specific ions, like calcium (Ca2+), in archaeal metabolism is not fully understood.
• Methanothermobacter thermautotrophicus is a model organism for studying methanogenesis.

Purpose of the Study:

• To investigate the effect of calcium ions (Ca2+) on the growth and methanogenesis of Methanothermobacter thermautotrophicus.
• To determine the dependency of methane formation on external Ca2+ concentration.
• To explore the potential Ca2+-dependent steps in the methanogenesis pathway.

Main Methods:

• Culturing Methanothermobacter thermautotrophicus under varying Ca2+ conditions.
• Utilizing calcium chelators (ethylene glycol bis(2-aminoethylether)-N,N,N',N'-tetra-acetic acid) and ionophores (A23187) to manipulate intracellular Ca2+ levels.
• Employing inhibitors of Ca2+ transport (Co2+, Ni2+) to assess their impact on methanogenesis.
• Measuring methane production in resting and Ca2+-preloaded cell suspensions.

Main Results:

• Growth of Methanothermobacter thermautotrophicus was inhibited by calcium chelators and ionophores.
• Methane formation was highly dependent on external Ca2+ concentration in resting cells.
• Methanogenesis in Ca2+-preloaded cells showed a significant stimulation (400%).
• Inhibitors of Ca2+ transport (Co2+, Ni2+) strongly inhibited methanogenesis.

Conclusions:

• Calcium ions (Ca2+) play a critical role in both the growth and methanogenesis of Methanothermobacter thermautotrophicus.
• Methanogenesis can be directly activated by Ca2+ ions, suggesting a Ca2+-dependent step within the pathway.
• These findings imply that a specific enzyme involved in methanogenesis may be directly regulated by Ca2+.