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Max-Panck- Insitt Max-PanckntItLit für MarIne Mikrohlologle 3rernrnb Bibliothek 1entar Nr : /9 c Untersuchung der zellularen Fettsäuren von sulfatreduzierenden Bakterien aus kalten, marinen Sedimenten Dissertation zur Erlangung des Grades eines Doktors der Naturwissenschaften - Dr. rer. nat. — dem Fachbereich Biologie/Chemie der Universität Bremen vorgelegt von Martin Könneke geboren in Wolfsburg Juli 2001 Max-Panck-Insitt für Marine Mkrobkog BibHothe C&siusstr. 1 e D-28359 Bremen Die vorliegende Doktorarbeit wurde in der Zeit von September 1997 bis Juni 2001 am Max Planck-Institut fur Marine Mikrobiologie in Bremen angefertigt. Gutachter: Prof. Dr. Friedrich Widdel 2. Gutachter: Prof. Dr. Bo Barker Jørgensen Tag des Promotionskolloquiums: 20. August 2001 Inhaltsverzeichnis Abkürzungen Zusammenfassung 1 Teil 1: Darstellung der Ergebnisse im Gesamtzusammenhang A Einleitung 3 1. Mikrobieller Abbau von organischem Material in marinen Sedimenten 3 2. SRB in marinen Sedimenten 4 3. Psychrophile und psychrotolerante SRB 6 4. Physiologische Merkmale psychrophiler SRB 7 5. Zellulare Fettsäuren von SRB 9 6. Einfluß der Temperatur auf die Lipidfettsäurenzusammensetzung von Bakterien ii 7. Zielsetzung der Arbeit 16 B Ergebnisse und Diskussion 18 1. Einfluß der Temperatur auf die zellulare Fettsäurenzusammensetzung von marinen sulfatreduzierenden Bakterien 18 1.1. Zellulare Fettsäurenzusammensetzung von psychrophilen, psychrotoleranten und mesophilen SRB bei verschiedenen Wachstumstemperaturen 18 1.2. Wachstumsabhängige Fettsäuremuster von Desuljobacter hydmgenophilus bei wechselnden Temperaturen 19 2. Neueinordnung von Desiilfrbacterium phenolicinn als Desuijobacula phenolica comb. nov. und Beschreibung von Desulfotignuin bulticiim gen. nov., sp. nov. 20 2.1. Phylogenetische Charakterisierung mittels 1 6S rRNA Gensequenz Analyse 20 2.2. Physiologische und morphologische Merkmale 20 2.3. Chemotaxonomische Einordnung mittels zellularer Fettsäureanalyse 21 3. Charakterisierung der Mikroorganismenzusammensetzung von marinen Sedimenten mittels Phospholipidanalysen und Bestimmung der Lebendzellzahlen 21 3.1. Tiefenprofile der Phospholipidfettsäuren 21 3.2. Abschätzung der Bakterienzahlen mittels der MPN-Methode 23 3.3. Phylogenetische Einordnung der neuisolierten Reinkulturen aus Svalbard 23 4. Anreicherung und Isolierung von methanogenen Archaea aus permanent kalten. marinen Sedimenten (Svalbard) 25 4.1. Anreicherung und Isolierung 25 4.2. Morphologische und physiologische Charakterisierung 27 4.3. Phylogenetische Einordnung 27 C Literaturverzeichnis 30 Teil II: Publikationen 38 A Publikationsllste mit Erläuterungen 38 B Publikationen 40 1. Effect of temperature on the composition of cellular fatty acids in sulphate-reducing bacteria 40 2. Reclassification of Desiiift.bateriu,i, phenoluii,n as Desulfibucitla phenolwci“ comb. nov. and description of strain SaxT as Desiilfrtigzum balticuin gen. nov.. sp. nov. 56 3. Aerobic and sulfate-reducing bacterial communities of Arctic sediments characterized by phospholipid analysis and cultivation rnethods 72 4. Community structure and activity of sulfate-reducing bacteria in an intertidal surface-sediment: A multi-methods approach 90 Danksagung Abkürzungen A Arrheniuskonstante ACP Acyl carrier protein AVS Acid-volatile sulfide C-irm MS Combastion interfaced isotope ratio mass spectrometry CFA Cyclopropanfettsäure(n) d Tag D Diffusionskoeffizient DAPL 4 ‚6- Diamidino-2-phenylindol DGGE Denaturing gradient gel electrophoresis DSMZ Deutsche Sammlung von Mikroorganismen und Zellkulturen dwt dry weight eV Elektronenvolt Ed Aktivierungsenergie FAME Fettsäuremethylester FID Flammenionisationsdetektor FISH Fluoreszenz-in situ-Hybridisierung GC Gaschromatographie GC-C-IRMS Gaschromatography combustion interfaced isotope ratio mass spectrometry GC/MS Gaschromatographie/Massenspektroskopie h Stunde HPLC l-ligh performance liquid chromatography ICBM Institut für Chemie und Biologie des Meeres ICP-OES lnductively coupled plasma optical emission spectroscopy kPa Kilopascal MPN most-probable number MS Massenspektroskopie mlz Masse/Ladung OD Optische Dichte PCR Polymerase cham reaction PLFA Phospholipidfettsäuren R Allgemeine Gaskonstante = 8,31 JK‘rnol‘ S RB Sulfatreduzierende Bakterien SRR Sulfatreduktionsraten T Absolute Temperatur Maximale Wachstumstemperatur T1 Minimale Wachstumstemperatur Tri Optimale Wachstumstemperatur TOC Total organic carbon V-CDT Vienna Canyon Diablo Troilit VFA Volatile fatty acids v Reaktionsgeschwindigkeit oder Wachstumsrate Zusammenfassung Im Mittelpunkt der vorliegenden Dissertation standen Analysen der zellularen Fettsäurenzusammensetzung von verschiedenen sulfatreduzierenden Bakterien (SRB) aus marinen Habitaten. In vergleichenden Analysen wurde erstmals der Einfluß der Wachstumstemperatur und der Wachstumsphase auf die zellularen Fettsäurenzusammensetzungen von verschiedenen SRB in Reinkulturen untersucht. Ferner wurden in situ Analysen der Phospholipide an marinen Sedimenten der Arktis (Svalbard) und des Wattenmeers (Deutschland) durchgeführt, um durch den Nachweis von Biomarkern Hinweise über die Häufigkeit und die Verteilung unterschiedlicher Mikroorganismengruppen zu erhalten. Die Bestimmung der Lebendzellzahlen verschiedener stoffwechselphysiologischer Bakterien in Sedimenten aus Svalbard wurde mit der selektiven Isolierung von neuen Mikroorganismen in Reinkulturen bei konstant niedrigen Temperaturen verbunden. 1. Erstmalig konnte gezeigt werden, daß Angehörige der Gattung Desulfobacter die Fähigkeit besitzen, ihre Fettsäurenzusammensetzung an wechselnde Temperaturen anzupassen. Dadurch regulieren sie die temperaturabhängige Fluidität ihrer Lipidmembranen. Bei niedrigen Temperaturen (4—12 °C) besitzt Desulfobacter hydrogenophilus, wie die meisten psychrophilen oder moderat psychrophilen SRB, einen konstant hohen Anteil an fluiditäterhöhenden, cis-ungesättigten Fettsäuren. Dieser Anteil verringert sich bei der Erhöhung der Wachstumstemperatur auf Werte, wie sie in anderen mesophilen SRB gefunden wurden. Durch wachstumsabhängige Untersuchungen ‘3C-markiertem mit Substrat wurde gezeigt, daß diese Temperaturanpassung durch de novo Synthese der zellularen Fettsäuren stattfindet. Bei niedrigen Temperaturen konnte neben einer Neusynthese von ungesättigten Fettsäuren, eine Inhibierung der Synthese von cis-9, 1 0-Methylenhexadecansäure (cyc 17:0) und 1 0-Methyl-hexadecansäure (1 OMe 16:0) nachgewiesen werden. 2. Ein sulfatreduzierendes Bakterium, das aus marinem Küstensediment der Ostsee isoliert wurde, stellt hinsichtlich der 16S rRNA Gensequenz, der Morphologie und des zellularen Fettsäuremusters eine neue Gattung innerhalb der 6-Proteobakterien dar. Als Bezeichnung für den vollständig-oxidierenden Typenstamm wurde Desulfotignum balticum vorgeschlagen. Aufgrund der großen Ähnlichkeit der 16S rRNA Gensequenz, der Morphologie, der Physiologie und der Fettsäuremuster in Desulfobacterium phenolicuni und Desulfobacula toluolica wurden beide Stämme in der Gattung Desulfobaciila vereinigt. Als neue Bezeichnung für D. phenolietim wurde Desulfobacula phenolica vorgeschlagen. In Desuijobacula und Desulfr)tignum konnte die für Desiilfiibacter Arten als spezifisch geltende Fettsäure lOMel6:O nachgewiesen werden. Dieser Befund widerlegt die oft beschriebene Spezifität dieser Fettsäure als Biomarker für Angehörige der Gattung Desulfobucter in marinen Sedimenten. 3. Die in situ Analyse der Phospholipidfettsäuren in permanent kalten, marinen Sedimenten (Svalbard) zeigte ein für mannes Sediment typisches Tiefenprofil. Durch den Nachweis spezifischer Fettsäuren konnte ein Wechsel einer von aeroben Mikroorganismen dominierten oberen Sedimentschicht zu einer von anaeroben Bakterien dominierten tieferen Schicht gezeigt werden. Die für SRB spezifischen Biomarker il7:l und lOMel6:O konnten nur in geringen Konzentrationen nachgewiesen werden und zeigten maximale Werte in der obersten Sedimentschicht. Die Phospholipidfettsäuren-Profile waren in guter Übereinstimmung mit der Tiefenverteilung von kultivierbaren aeroben Bakterien und SRB, die über die most-probable number (MPN) Methode ermittelt wurden. Aus den Verdünnungsserien konnten verschiedene Reinkulturen isoliert werden, die eine enge Verwandtschaft zu bekannten psychrophilen Bakterien zeigten. Drei sulfatreduzierende Reinkulturen, denen Wasserstoff als Elektronendonator diente, stellen aufgrund ihrer 16S rRNA Gensequenzen neue Gattungen innerhalb der -Proteobakterien dar. Die geringen Konzentrationen der für Desiilfovibrio spezifischen Biomarker und deren Abwesenheit in den höchsten MPN Verdünnungsreihen weisen auf eine nur untergeordnete ökologische Bedeutung dieser Gattung Desti1/vibrio in diesem kalten Habitat hin. 4. Aus permanent kaltem. marinem Sediment (Svalbard) konnten mit Methanol oder Trimethylamin methanogene Archaea selektiv bei niedrigen Temperaturen in Reinkultur isoliert werden. Zwei der sieben Isolate zeigen aufgrund ihrer 16S rRNA-Gensequenzen und ihrer Morphologie große Ähnlichkeiten zu den methylotrophen Archaea Methanolobus taylorii bzw. Methanococcoides burtonil. Die isolierten Stämme verwerten wie ihre nahen Verwandten lediglich Methanol und Trimethylamin. Die Reinkulturen sind die ersten beschriebenen Methanogenen, die aus permanent kalten, marinen Sedimenten der Arktis isoliert wurden. 2 Teil 1: Darstellung der Ergebnisse im Gesamtzusammenhang A Einleitung 1. Mikrobieller Abbau von organischem Material in marinen Sedimenten In den Meeren findet die Primärproduktion von organischem Material durch phototrophe Organismen in den oberflächennahen
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