title: Novel long-chain anteiso-alkanes and anteiso-alkanoic acids in Antarctic rocks colonized by living and fossil cryptoendolithic microorganisms.
abstract: Saponified extracts of rock samples colonized by cryptoendolithic microbial communities from the McMurdo Dry Valleys of Southern Victoria Land, Antarctica, were separated into hydrocarbon and fatty acid fractions by silica gel column chromatography.  Hydrocarbons and methyl esters of fatty acids were analyzed by capillary gas chromatography-mass spectrometry.  Unusually, a suite of long-chain anteiso-alkanes (a-C20 to a-C30) and anteiso-alkanoic acids (a-C20 to a-C30) were detected in many samples, together with straight-chain, branched and/or cyclic and acyclic isoprenoid compounds.  These novel compounds are probably derived from unidentified heterotrophic bacteria or symbiotic processes in a unique microbial community in the Antarctic cold desert and suggest the occurrence of a special biosynthetic pathway.  Long-chain anteiso-alkanes are probably formed through microbial decarboxylation of corresponding anteiso-alkanoic acids.  They may serve as new biomarkers in environmental and geochemical studies.
authors.affiliation: Department of Chemistry, University of Tokyo, Japan.
authors.forename: G I
authors.initials: GI
authors.lastname: Matsumoto
authors.forename: E I
authors.initials: EI
authors.lastname: Friedmann
authors.forename: K
authors.initials: K
authors.lastname: Watanuki
authors.forename: R
authors.initials: R
authors.lastname: Ocampo-Friedmann
mesh_terms: D000473:Alkanes / Q000032:analysis* / Q000737:chemistry; D000864:Antarctic Regions; D001419:Bacteria / Q000737:chemistry*; D002264:Carboxylic Acids / Q000032:analysis* / Q000737:chemistry; D004783:Environmental Microbiology; D005227:Fatty Acids / Q000032:analysis*; D005580:Fossils; D008401:Gas Chromatography-Mass Spectrometry; D055593:Geological Phenomena; D005844:Geology; D006838:Hydrocarbons / Q000032:analysis*; D008011:Lichens / Q000737:chemistry*; D012987:Soil
chemical_list: D000473:Alkanes; D002264:Carboxylic Acids; D005227:Fatty Acids; D006838:Hydrocarbons; D012987:Soil