title: Archaeoglobus fulgidus couples CO oxidation to sulfate reduction and acetogenesis with transient formate accumulation.
abstract: The genome sequence of Archaeoglobus fulgidus VC16 encodes three CO dehydrogenase genes. Here we explore the capacity of A. fulgidus to use CO as growth substrate. Archaeoglobus fulgidus VC16 was successfully adapted to growth medium that contained sulfate and CO. In the presence of CO and sulfate the culture OD(660) increased to 0.41 and sulfide, carbon dioxide, acetate and formate were formed. Accumulation of formate was transient. Similar results, except that no sulfide was formed, were obtained when sulfate was omitted. Hydrogen was never detected. Under the conditions tested, the observed concentrations of acetate (18 mM) and formate (8.2 mM) were highest in cultures without sulfate. Proton NMR spectroscopy indicated that CO2, and not CO, is the precursor of formate and the methyl group of acetate. Methylviologen-dependent formate dehydrogenase activity (1.4 micromol formate oxidized min(-1) mg(-1)) was detected in cell-free extracts and expected to have a role in formate reuptake. It is speculated that formate formation proceeds through hydrolysis of formyl-methanofuran or formyl-tetrahydromethanopterin. This study demonstrates that A. fulgidus can grow chemolithoautotrophically with CO as acetogen, and is not strictly dependent on the presence of sulfate, thiosulfate or other sulfur compounds as electron acceptor.
authors.affiliation: Laboratory of Microbiology, Wageningen University, H. v. Suchtelenweg 4, 6703 CT, Wageningen, The Netherlands. anne-meint.henstra@wur.nl
authors.forename: Anne M
authors.initials: AM
authors.lastname: Henstra
authors.forename: Cor
authors.initials: C
authors.lastname: Dijkema
authors.forename: Alfons J M
authors.initials: AJ
authors.lastname: Stams
mesh_terms: D000085:Acetates / Q000378:metabolism*; D019611:Archaeoglobus fulgidus / Q000378:metabolism* / Q000502:physiology; D002247:Carbon Isotopes; D002248:Carbon Monoxide / Q000378:metabolism*; D052837:Chemoautotrophic Growth / Q000502:physiology*; D002851:Chromatography, High Pressure Liquid; D005560:Formate Dehydrogenases / Q000378:metabolism; D005561:Formates / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D010084:Oxidation-Reduction; D013431:Sulfates / Q000378:metabolism*
chemical_list: D000085:Acetates; D002247:Carbon Isotopes; D005561:Formates; D013431:Sulfates; C030544:formic acid; D002248:Carbon Monoxide; D005560:Formate Dehydrogenases