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Archives of Microbiology

, Volume 167, Issue 1, pp 19–23 | Cite as

Pathways of autotrophic CO2 fixation and of dissimilatory nitrate reduction to N2O in Ferroglobus placidus

  • J. A. Vorholt
  • Doris Hafenbradl
  • Karl O. Stetter
  • Rudolf K. Thauer
Original paper

Abstract

The strictly anaerobic Archaeon Ferroglobus placidus was grown chemolithoautotrophically on H2 and nitrate and analyzed for enzymes and coenzymes possibly involved in autotrophic CO2 fixation. The following enzymes were found [values in parentheses = μmol min–1 (mg protein)–1]: formylmethanofuran dehydrogenase (0.2), formylmethanofuran:tetrahydromethanopterin formyltransferase (0.6), methenyltetrahydromethanopterin cyclohydrolase (10), F420-dependent methylenetetrahydromethanopterin dehydrogenase (1.5), F420-dependent methylenetetrahydromethanopterin reductase (0.4), and carbon monoxide dehydrogenase (0.1). The cells contained coenzyme F420 (0.4 nmol/mg protein), tetrahydromethanopterin (0.9 nmol/ mg protein), and cytochrome b (4 nmol/mg membrane protein). From the enzyme and coenzyme composition of the cells, we deduced that autotrophic CO2 fixation in F. placidus proceeds via the carbon monoxide dehydrogenase pathway as in autotrophically growing Archaeoglobus and Methanoarchaea species. Evidence is also presented that cell extracts of F. placidus catalyze the reduction of two molecules of nitrite to 1 N2O with NO as intermediate (0.1 μmol N2O formed per min and mg protein), showing that – at least in principle –F. placidus has a denitrifying capacity.

Key words Autotrophic CO2 fixation Dissimilatory nitrate reduction Archaeoglobus species Methanogenic Archaea Methanofuran Tetrahydromethanopterin Coenzyme F420 Cytochromes 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • J. A. Vorholt
    • 1
  • Doris Hafenbradl
    • 2
  • Karl O. Stetter
    • 2
  • Rudolf K. Thauer
    • 1
  1. 1.Max-Planck-Institut für terrestrische Mikrobiologie und Laboratorium für Mikrobiologie des Fachbereichs Biologie, Philipps-Universität, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany Tel. +49-6421-178-200; Fax +49-6421-178-209DE
  2. 2.Universität Regensburg, Lehrstuhl für Mikrobiologie, Universitätsstrasse 31, D-93053 Regensburg, GermanyDE

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