METABOLIC-REGULATION IN METHANOGENIC ARCHAEA DURING GROWTH ON HYDROGEN AND CO2

Methanogenic Archaea represent a unique group of micro-organisms in th eir ability to derive their energy for growth from the conversion of t heir 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 natura l habitats and under laboratory conditions. In this review the bio-ene rgetic consequences of the variations in hydrogen supply will be inves tigated. It will be described how the organisms seem to be equipped as to their methanogenic apparatus to cope with extremes in hydrogen ava ilability and how they could respond to hydrogen changes by the regula tion of their metabolism.