Modern subsurface bacteria in pristine 2.7 Ga-old fossil stromatolite drillcore samples from the Fortescue Group, Western Australia.

<h4>Background</h4>Several abiotic processes leading to the formation of life-like signatures or later contamination with actual biogenic traces can blur the interpretation of the earliest fossil record. In recent years, a large body of evidence showing the occurrence of diverse and acti...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Emmanuelle Gérard, David Moreira, Pascal Philippot, Martin J Van Kranendonk, Purificación López-García
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2009
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/fb9105b67e814ced809bded195521e01
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:fb9105b67e814ced809bded195521e01
record_format	dspace
spelling	oai:doaj.org-article:fb9105b67e814ced809bded195521e012021-11-25T06:23:01ZModern subsurface bacteria in pristine 2.7 Ga-old fossil stromatolite drillcore samples from the Fortescue Group, Western Australia.1932-620310.1371/journal.pone.0005298https://doaj.org/article/fb9105b67e814ced809bded195521e012009-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/19396360/?tool=EBIhttps://doaj.org/toc/1932-6203<h4>Background</h4>Several abiotic processes leading to the formation of life-like signatures or later contamination with actual biogenic traces can blur the interpretation of the earliest fossil record. In recent years, a large body of evidence showing the occurrence of diverse and active microbial communities in the terrestrial subsurface has accumulated. Considering the time elapsed since Archaean sedimentation, the contribution of subsurface microbial communities postdating the rock formation to the fossil biomarker pool and other biogenic remains in Archaean rocks may be far from negligible.<h4>Methodology/principal findings</h4>In order to evaluate the degree of potential contamination of Archean rocks by modern microorganisms, we looked for the presence of living indigenous bacteria in fresh diamond drillcores through 2,724 Myr-old stromatolites (Tumbiana Formation, Fortescue Group, Western Australia) using molecular methods based on the amplification of small subunit ribosomal RNA genes (SSU rDNAs). We analyzed drillcore samples from 4.3 m and 66.2 m depth, showing signs of meteoritic alteration, and also from deeper "fresh" samples showing no apparent evidence for late stage alteration (68 m, 78.8 m, and 99.3 m). We also analyzed control samples from drilling and sawing fluids and a series of laboratory controls to establish a list of potential contaminants introduced during sample manipulation and PCR experiments. We identified in this way the presence of indigenous bacteria belonging to Firmicutes, Actinobacteria, and Alpha-, Beta-, and Gammaproteobacteria in aseptically-sawed inner parts of drillcores down to at least 78.8 m depth.<h4>Conclusions/significance</h4>The presence of modern bacterial communities in subsurface fossil stromatolite layers opens the possibility that a continuous microbial colonization had existed in the past and contributed to the accumulation of biogenic traces over geological timescales. This finding casts shadow on bulk analyses of early life remains and makes claims for morphological, chemical, isotopic, and biomarker traces syngenetic with the rock unreliable in the absence of detailed contextual analyses at microscale.Emmanuelle GérardDavid MoreiraPascal PhilippotMartin J Van KranendonkPurificación López-GarcíaPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 4, Iss 4, p e5298 (2009)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Emmanuelle Gérard David Moreira Pascal Philippot Martin J Van Kranendonk Purificación López-García Modern subsurface bacteria in pristine 2.7 Ga-old fossil stromatolite drillcore samples from the Fortescue Group, Western Australia.
description	<h4>Background</h4>Several abiotic processes leading to the formation of life-like signatures or later contamination with actual biogenic traces can blur the interpretation of the earliest fossil record. In recent years, a large body of evidence showing the occurrence of diverse and active microbial communities in the terrestrial subsurface has accumulated. Considering the time elapsed since Archaean sedimentation, the contribution of subsurface microbial communities postdating the rock formation to the fossil biomarker pool and other biogenic remains in Archaean rocks may be far from negligible.<h4>Methodology/principal findings</h4>In order to evaluate the degree of potential contamination of Archean rocks by modern microorganisms, we looked for the presence of living indigenous bacteria in fresh diamond drillcores through 2,724 Myr-old stromatolites (Tumbiana Formation, Fortescue Group, Western Australia) using molecular methods based on the amplification of small subunit ribosomal RNA genes (SSU rDNAs). We analyzed drillcore samples from 4.3 m and 66.2 m depth, showing signs of meteoritic alteration, and also from deeper "fresh" samples showing no apparent evidence for late stage alteration (68 m, 78.8 m, and 99.3 m). We also analyzed control samples from drilling and sawing fluids and a series of laboratory controls to establish a list of potential contaminants introduced during sample manipulation and PCR experiments. We identified in this way the presence of indigenous bacteria belonging to Firmicutes, Actinobacteria, and Alpha-, Beta-, and Gammaproteobacteria in aseptically-sawed inner parts of drillcores down to at least 78.8 m depth.<h4>Conclusions/significance</h4>The presence of modern bacterial communities in subsurface fossil stromatolite layers opens the possibility that a continuous microbial colonization had existed in the past and contributed to the accumulation of biogenic traces over geological timescales. This finding casts shadow on bulk analyses of early life remains and makes claims for morphological, chemical, isotopic, and biomarker traces syngenetic with the rock unreliable in the absence of detailed contextual analyses at microscale.
format	article
author	Emmanuelle Gérard David Moreira Pascal Philippot Martin J Van Kranendonk Purificación López-García
author_facet	Emmanuelle Gérard David Moreira Pascal Philippot Martin J Van Kranendonk Purificación López-García
author_sort	Emmanuelle Gérard
title	Modern subsurface bacteria in pristine 2.7 Ga-old fossil stromatolite drillcore samples from the Fortescue Group, Western Australia.
title_short	Modern subsurface bacteria in pristine 2.7 Ga-old fossil stromatolite drillcore samples from the Fortescue Group, Western Australia.
title_full	Modern subsurface bacteria in pristine 2.7 Ga-old fossil stromatolite drillcore samples from the Fortescue Group, Western Australia.
title_fullStr	Modern subsurface bacteria in pristine 2.7 Ga-old fossil stromatolite drillcore samples from the Fortescue Group, Western Australia.
title_full_unstemmed	Modern subsurface bacteria in pristine 2.7 Ga-old fossil stromatolite drillcore samples from the Fortescue Group, Western Australia.
title_sort	modern subsurface bacteria in pristine 2.7 ga-old fossil stromatolite drillcore samples from the fortescue group, western australia.
publisher	Public Library of Science (PLoS)
publishDate	2009
url	https://doaj.org/article/fb9105b67e814ced809bded195521e01
work_keys_str_mv	AT emmanuellegerard modernsubsurfacebacteriainpristine27gaoldfossilstromatolitedrillcoresamplesfromthefortescuegroupwesternaustralia AT davidmoreira modernsubsurfacebacteriainpristine27gaoldfossilstromatolitedrillcoresamplesfromthefortescuegroupwesternaustralia AT pascalphilippot modernsubsurfacebacteriainpristine27gaoldfossilstromatolitedrillcoresamplesfromthefortescuegroupwesternaustralia AT martinjvankranendonk modernsubsurfacebacteriainpristine27gaoldfossilstromatolitedrillcoresamplesfromthefortescuegroupwesternaustralia AT purificacionlopezgarcia modernsubsurfacebacteriainpristine27gaoldfossilstromatolitedrillcoresamplesfromthefortescuegroupwesternaustralia
_version_	1718413840731865088

Modern subsurface bacteria in pristine 2.7 Ga-old fossil stromatolite drillcore samples from the Fortescue Group, Western Australia.

Ejemplares similares