title: Biosynthesis of hopanoids by sulfate-reducing bacteria (genus Desulfovibrio).
abstract: Sulfate reduction accounts for about a half of the remineralization of organic carbon in anoxic marine shelf regions. Moreover, it was already a major microbial process in the very early ocean at least 2.4 billion years before the present. Here we demonstrate for the first time the capability of sulfate-reducing bacteria (SRB) to biosynthesize hopanoids, compounds that are quantitatively important and widely distributed biomarkers in recent and fossil sediments dating back to the late Archean. We found high concentrations (9.8-12.3 mg per gram of dry cells) of non-extended and extended bacteriohopanoids (bacteriohopanetetrol, aminobacteriohopanetriol, aminobacteriohopanetetrol) in pure cultures of SRB belonging to the widely distributed genus Desulfovibrio. Biohopanoids were found--considered as membrane rigidifiers--in more than 50% of bacterial species analysed so far. However, their biosynthesis appeared to be restricted to aerobes or facultative anaerobes with a very few recently described exceptions. Consequently, findings of sedimentary hopanoids are often used as indication for oxygenated settings. Nevertheless, our findings shed new light on the presence of hopanoids in specific anoxic settings and suggests that SRB are substantial sources of this quantitatively important lipid class in recent but also past anoxic environments.
authors.affiliation: Institute of Biogeochemistry and Marine Chemistry, University of Hamburg, Bundesstrasse 55, 20146 Hamburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Blumenberg
authors.forename: Martin
authors.initials: M
authors.lastname: Krüger
authors.forename: Katja
authors.initials: K
authors.lastname: Nauhaus
authors.forename: Helen M
authors.initials: HM
authors.lastname: Talbot
authors.forename: Birte I
authors.initials: BI
authors.lastname: Oppermann
authors.forename: Richard
authors.initials: R
authors.lastname: Seifert
authors.forename: Thomas
authors.initials: T
authors.lastname: Pape
authors.forename: Walter
authors.initials: W
authors.lastname: Michaelis
mesh_terms: D001105:Archaea / Q000378:metabolism; D001421:Bacteria, Anaerobic / Q000302:isolation & purification / Q000378:metabolism*; D001431:Bacteriological Techniques; D015415:Biomarkers / Q000737:chemistry / Q000378:metabolism; D002247:Carbon Isotopes; D003901:Desulfovibrio / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D008563:Membrane Lipids / Q000096:biosynthesis* / Q000737:chemistry; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*; D013729:Terpenes / Q000737:chemistry / Q000378:metabolism; D014315:Triterpenes / Q000737:chemistry / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D002247:Carbon Isotopes; D008563:Membrane Lipids; D012336:RNA, Ribosomal, 16S; D013729:Terpenes; D014315:Triterpenes