ENZYMES AND COENZYMES OF THE CARBON-MONOXIDE DEHYDROGENASE PATHWAY FOR AUTOTROPHIC CO2 FIXATION IN ARCHAEOGLOBUS-LITHOTROPHICUS AND THE LACK OF CARBON-MONOXIDE DEHYDROGENASE IN THE HETEROTROPHIC A-PROFUNDUS

Archaeoglobus lithotrophicus is a hyperthermophilic Archaeon that grow s on H-2 and sulfate as energy sources and CO2 as sole carbon source. The autotrophic sulfate reducer was shown to contain all the enzyme ac tivities and coenzymes of the reductive carbon monoxide dehydrogenase pathway for autotrophic CO2 fixation as operative in methanogenic Arch aea. With the exception of carbon monoxide dehydrogenase these enzymes and coenzymes were also found in A. profundus. This organism grows li thotrophically on H-2 and sulfate, but differs from A. lithotrophicus in that it cannot grow autotrophically: A. profundus requires acetate and CO2 for biosynthesis. The absence of carbon monoxide dehydrogenase in A. profundus is substantiated by the observation that this organis m, in contrast to A. lithotrophicus, is not mini-methanogenic and cont ains only relatively low concentrations of corrinoids.