title: Preservation and evolution of organic matter during experimental fossilisation of the hyperthermophilic archaea Methanocaldococcus jannaschii.
abstract: Identification of the earliest traces of life is made difficult by the scarcity of the preserved microbial remains and by the alteration and potential contamination of the organic matter (OM) content of rocks. These factors can confuse interpretations of the biogenicity and syngenicity of fossilised structures and organic molecules found in ancient rocks. In order to improve our knowledge of the fossilisation processes and their effects at the molecular level, we made a preliminary study of the fate of OM during experimental fossilisation. Changes in the composition and quantity of amino acids, monosaccharides and fatty acids were followed with HPLC, GC and GC-MS analyses during 1 year of silicification of the hyperthermophilic Archaea Methanocaldococcus jannaschii. Although the cells themselves did not fossilise and the accompanying extracellular polymeric substances (EPS) did, our analyses showed that the OM initially present in both cells and EPS was uniformly preserved in the precipitated silica, with amino acids and fatty acids being the best preserved compounds. This study thus completes previous data obtained by electron microscopy investigations of simulated microbial fossilisation and can help better identification and interpretation of microbial biosignatures in both ancient rocks and in recent hydrothermal formations and sediments.
authors.affiliation: Centre de Biophysique Moléculaire - UPR 4301, CNRS, Rue Charles Sadron, 45071, Orléans Cedex 2, France. francois.orange@gmail.com
authors.forename: François
authors.initials: F
authors.lastname: Orange
authors.forename: Jean-Robert
authors.initials: JR
authors.lastname: Disnar
authors.forename: Pascale
authors.initials: P
authors.lastname: Gautret
authors.forename: Frances
authors.initials: F
authors.lastname: Westall
authors.forename: Nadège
authors.initials: N
authors.lastname: Bienvenu
authors.forename: Nathalie
authors.initials: N
authors.lastname: Lottier
authors.forename: Daniel
authors.initials: D
authors.lastname: Prieur
mesh_terms: D005075:Biological Evolution; D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D005580:Fossils; D008401:Gas Chromatography-Mass Spectrometry; D019015:Geologic Sediments / Q000737:chemistry*; D017015:Methanococcales / Q000737:chemistry*; D009930:Organic Chemicals / Q000737:chemistry*; D000069497:Origin of Life
chemical_list: D009930:Organic Chemicals