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Title: Nanoscale detection of organic signatures in carbonatemicrobialites

Abstract

Microbialites are sedimentary deposits associated withmicrobialmat communities and are thought to be evidence of some of theoldest life on Earth. Despite extensive studies of such deposits, littleis known about the role of microorganisms in their formation. Inaddition, unambiguous criteria proving their biogenicity have yet to beestablished. In this study, we characterize modern calcareousmicrobialites from the alkaline Lake Van, Turkey, at the nanometer scaleby combining x-ray and electron microscopies. We describe a simple way tolocate microorganisms entombed in calcium carbonate precipitates byprobing aromatic carbon functional groups and peptide bonds. Near-edgex-ray absorption fine structure spectra at the C and N K-edges provideunique signatures for microbes. Aragonite crystals, which range in sizefrom 30 to 100nm, comprise the largest part of the microbialites. Thesecrystals are surrounded by a 10-nm-thick amorphous calcium carbonatelayer containing organic molecules and areembedded in an organic matrix,likely consisting of polysaccharides, which helps explain the unusualsizes and shapes of these crystals. These results provide biosignaturesfor these deposits and suggest that microbialorganisms significantlyimpacted the mineralogy of Lake Vancarbonates.

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
COLLABORATION - U. ofParis/France
Sponsoring Org.:
USDOE Director. Office of Science. Basic EnergySciences
OSTI Identifier:
926577
Report Number(s):
LBNL-60872
R&D Project: CB1102; BnR: KC0302030
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Proceedings of the National Academy; Journal Volume: 103; Journal Issue: 25; Related Information: Journal Publication Date: June 20,2006
Country of Publication:
United States
Language:
English
Subject:
37; aragonite biosignature biomineralizationspectromicroscopy

Citation Formats

Benzerara, Karim, Menguy, Nicolas, Lopez-Garcia, Purificacion, Yoon, Tae-Hyun, Kazmierczak, Jozef, Tyliszczak, Tolek, Guyot, Francois, and Brown Jr., Gordon E.. Nanoscale detection of organic signatures in carbonatemicrobialites. United States: N. p., 2007. Web.
Benzerara, Karim, Menguy, Nicolas, Lopez-Garcia, Purificacion, Yoon, Tae-Hyun, Kazmierczak, Jozef, Tyliszczak, Tolek, Guyot, Francois, & Brown Jr., Gordon E.. Nanoscale detection of organic signatures in carbonatemicrobialites. United States.
Benzerara, Karim, Menguy, Nicolas, Lopez-Garcia, Purificacion, Yoon, Tae-Hyun, Kazmierczak, Jozef, Tyliszczak, Tolek, Guyot, Francois, and Brown Jr., Gordon E.. Mon . "Nanoscale detection of organic signatures in carbonatemicrobialites". United States. doi:.
@article{osti_926577,
title = {Nanoscale detection of organic signatures in carbonatemicrobialites},
author = {Benzerara, Karim and Menguy, Nicolas and Lopez-Garcia, Purificacion and Yoon, Tae-Hyun and Kazmierczak, Jozef and Tyliszczak, Tolek and Guyot, Francois and Brown Jr., Gordon E.},
abstractNote = {Microbialites are sedimentary deposits associated withmicrobialmat communities and are thought to be evidence of some of theoldest life on Earth. Despite extensive studies of such deposits, littleis known about the role of microorganisms in their formation. Inaddition, unambiguous criteria proving their biogenicity have yet to beestablished. In this study, we characterize modern calcareousmicrobialites from the alkaline Lake Van, Turkey, at the nanometer scaleby combining x-ray and electron microscopies. We describe a simple way tolocate microorganisms entombed in calcium carbonate precipitates byprobing aromatic carbon functional groups and peptide bonds. Near-edgex-ray absorption fine structure spectra at the C and N K-edges provideunique signatures for microbes. Aragonite crystals, which range in sizefrom 30 to 100nm, comprise the largest part of the microbialites. Thesecrystals are surrounded by a 10-nm-thick amorphous calcium carbonatelayer containing organic molecules and areembedded in an organic matrix,likely consisting of polysaccharides, which helps explain the unusualsizes and shapes of these crystals. These results provide biosignaturesfor these deposits and suggest that microbialorganisms significantlyimpacted the mineralogy of Lake Vancarbonates.},
doi = {},
journal = {Proceedings of the National Academy},
number = 25,
volume = 103,
place = {United States},
year = {Mon May 07 00:00:00 EDT 2007},
month = {Mon May 07 00:00:00 EDT 2007}
}
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