Metabolic regulation in methanogenic archaea during growth on hydrogen and CO2.

Methanogenic Archaea represent a unique group of micro-organisms in their ability to derive their energy for growth from the conversion of their substrates to methane. The common substrates are hydrogen and CO2. The energy obtained in the latter conversion is highly dependent on the hydrogen concentration which may dramatically vary in their natural habitats and under laboratory conditions. In this review the bio-energetic consequences of the variations in hydrogen supply will be investigated. It will be described how the organisms seem to be equipped as to their methanogenic apparatus to cope with extremes in hydrogen availability and how they could respond to hydrogen changes by the regulation of their metabolism.