Molecular characterization of cyanobacterial silicification using synchrotron infrared micro-spectroscopy

Liane G. Benning, V. R. Phoenix, N. Yee, M. J. Tobin

Research output: Contribution to journalArticle

118 Citations (Scopus)

Abstract

Synchrotron-based Fourier-transform infrared (SR-FTIR) micro-spectroscopy was used to determine the concentration-dependent response of the organic structure of live cyanobacterial cells to silicification. Mid-infrared (4000-600 cm-1) measurements carried out on single filaments and sheaths of the cyanobacteria Calothrix sp. (strain KC97) were used to monitor the interaction between a polymerizing silica solution and the organic functional groups of the cells during progressive silicification. Spectra of whole-cells and sheaths were analyzed and the spectral features were assigned to specific functional groups related to the cell: lipids (-CH2 and -CH3; at 2870-2960 cm-1), fatty acids (>C=O at 1740 cm-1), proteins (amides I and II at 1650 and 1540 cm-1), nucleic acids (>P=O 1240 cm-1), carboxylic acids (C-O at 1392 cm-1), and polysaccharides (C-O between 1165 and 1030 cm-1). These vibrations and the characteristic vibrations for silica (Si-O between 1190 and 1060 cm-1; to some extent overlapping with the C-O frequencies of polysaccharides and Si-O at 800 cm-1) were used to follow the progress of silicification. Relative to unsilicified samples, the intensity of the combined C-O/Si-O vibration band increased considerably over the course of the silicification (whole-cells by >90% and sheath by ∼75%). This increase is a consequence of (1) extensive growth of the sheath in response to the silicification, and (2) the formation of thin amorphous silica layers on the sheath. The formation of a silica specific band (∼800 cm-1) indicates, however, that the precipitation of amorphous silica is controlled by the dehydroxylation of abiotically formed silanol groups.

LanguageEnglish
Pages729-741
Number of pages13
JournalGeochimica et Cosmochimica Acta
Volume68
Issue number4
Early online date6 Feb 2004
DOIs
Publication statusPublished - 15 Feb 2004
Externally publishedYes

Fingerprint

silicification
Synchrotrons
Silicon Dioxide
silica
spectroscopy
Spectroscopy
Infrared radiation
vibration
polysaccharide
Functional groups
functional group
Polysaccharides
dehydroxylation
nucleic acid
carboxylic acid
Carboxylic Acids
Amides
Nucleic Acids
Fourier transform
cyanobacterium

Keywords

  • infrared spectroscopy
  • silicification
  • cyanobacterium
  • geomicrobiology

Cite this

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title = "Molecular characterization of cyanobacterial silicification using synchrotron infrared micro-spectroscopy",
abstract = "Synchrotron-based Fourier-transform infrared (SR-FTIR) micro-spectroscopy was used to determine the concentration-dependent response of the organic structure of live cyanobacterial cells to silicification. Mid-infrared (4000-600 cm-1) measurements carried out on single filaments and sheaths of the cyanobacteria Calothrix sp. (strain KC97) were used to monitor the interaction between a polymerizing silica solution and the organic functional groups of the cells during progressive silicification. Spectra of whole-cells and sheaths were analyzed and the spectral features were assigned to specific functional groups related to the cell: lipids (-CH2 and -CH3; at 2870-2960 cm-1), fatty acids (>C=O at 1740 cm-1), proteins (amides I and II at 1650 and 1540 cm-1), nucleic acids (>P=O 1240 cm-1), carboxylic acids (C-O at 1392 cm-1), and polysaccharides (C-O between 1165 and 1030 cm-1). These vibrations and the characteristic vibrations for silica (Si-O between 1190 and 1060 cm-1; to some extent overlapping with the C-O frequencies of polysaccharides and Si-O at 800 cm-1) were used to follow the progress of silicification. Relative to unsilicified samples, the intensity of the combined C-O/Si-O vibration band increased considerably over the course of the silicification (whole-cells by >90{\%} and sheath by ∼75{\%}). This increase is a consequence of (1) extensive growth of the sheath in response to the silicification, and (2) the formation of thin amorphous silica layers on the sheath. The formation of a silica specific band (∼800 cm-1) indicates, however, that the precipitation of amorphous silica is controlled by the dehydroxylation of abiotically formed silanol groups.",
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Molecular characterization of cyanobacterial silicification using synchrotron infrared micro-spectroscopy. / Benning, Liane G.; Phoenix, V. R.; Yee, N.; Tobin, M. J.

In: Geochimica et Cosmochimica Acta, Vol. 68, No. 4, 15.02.2004, p. 729-741.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Molecular characterization of cyanobacterial silicification using synchrotron infrared micro-spectroscopy

AU - Benning, Liane G.

AU - Phoenix, V. R.

AU - Yee, N.

AU - Tobin, M. J.

PY - 2004/2/15

Y1 - 2004/2/15

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AB - Synchrotron-based Fourier-transform infrared (SR-FTIR) micro-spectroscopy was used to determine the concentration-dependent response of the organic structure of live cyanobacterial cells to silicification. Mid-infrared (4000-600 cm-1) measurements carried out on single filaments and sheaths of the cyanobacteria Calothrix sp. (strain KC97) were used to monitor the interaction between a polymerizing silica solution and the organic functional groups of the cells during progressive silicification. Spectra of whole-cells and sheaths were analyzed and the spectral features were assigned to specific functional groups related to the cell: lipids (-CH2 and -CH3; at 2870-2960 cm-1), fatty acids (>C=O at 1740 cm-1), proteins (amides I and II at 1650 and 1540 cm-1), nucleic acids (>P=O 1240 cm-1), carboxylic acids (C-O at 1392 cm-1), and polysaccharides (C-O between 1165 and 1030 cm-1). These vibrations and the characteristic vibrations for silica (Si-O between 1190 and 1060 cm-1; to some extent overlapping with the C-O frequencies of polysaccharides and Si-O at 800 cm-1) were used to follow the progress of silicification. Relative to unsilicified samples, the intensity of the combined C-O/Si-O vibration band increased considerably over the course of the silicification (whole-cells by >90% and sheath by ∼75%). This increase is a consequence of (1) extensive growth of the sheath in response to the silicification, and (2) the formation of thin amorphous silica layers on the sheath. The formation of a silica specific band (∼800 cm-1) indicates, however, that the precipitation of amorphous silica is controlled by the dehydroxylation of abiotically formed silanol groups.

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