title: The preservation and degradation of filamentous bacteria and biomolecules within iron oxide deposits at Rio Tinto, Spain.
abstract: One of the keys to understanding and identifying life on other planets is to study the preservation of organic compounds and their precursor micro-organisms on Earth. Rio Tinto in southwestern Spain is a well documented site of microbial preservation within iron sulphates and iron oxides over a period of 2.1 Ma. This study has investigated the preservation of filamentous iron oxidising bacteria and organics through optical microscopy, scanning electron microscopy (SEM) and Fourier transform infra-red (FTIR) spectroscopy, from laboratory cultures of natural samples to contemporary natural materials to million-year old river terraces. Up to 40% elemental carbon and >7% nitrogen has been identified within microbial filaments and cell clusters in all samples through SEM EDS analyses. FTIR spectroscopy identified C-H(x) absorption bands between 2960 and 2800 cm(-1), Amide I and II absorption bands at 1656 and 1535 cm(-1), respectively and functional group vibrations from within nucleic acids at 917, 1016 and 1124 cm(-1). Absorption bands tracing the diagenetic transformation of jarosite to goethite to hematite through the samples are also identified. This combination of mineralogy, microbial morphology and biomolecular evidence allows us to further understand how organic fossils are created and preserved in iron-rich environments, and ultimately will aid in the search for the earliest life on Earth and potential organics on Mars.
authors: Centre for Planetary Science and Exploration (CPSX), The University of Western Ontario, London, Ontario, Canada. lpresto5@uwo.ca
authors: L J
authors: LJ
authors: Preston
authors: J
authors: J
authors: Shuster
authors: D
authors: D
authors: Fernández-Remolar
authors: N R
authors: NR
authors: Banerjee
authors: G R
authors: GR
authors: Osinski
authors: G
authors: G
authors: Southam
mesh_terms: D001419:Bacteria / Q000302:isolation & purification*; D001431:Bacteriological Techniques; D018929:Cell Culture Techniques; D005580:Fossils; D019015:Geologic Sediments / Q000737:chemistry / Q000382:microbiology*; D058085:Iron Compounds / Q000737:chemistry*; D009930:Organic Chemicals / Q000032:analysis; D045483:Rivers; D013030:Spain
chemical_list: D058085:Iron Compounds; D009930:Organic Chemicals