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CaCO3 precipitation in multilayered cyanobacterial mats: clues to explain the alternation of micrite and sparite layers in calcareous stromatolites.

Kaźmierczak J, Fenchel T, Kühl M, Kempe S, Kremer B, Łącka B, Małkowski K - Life (Basel) (2015)

Bottom Line: The d13C values were about 2‰ heavier in carbonates from the living cyanobacterial zones as compared to those generated in the purple bacterial zones.The generated CaCO3 morphs were highly similar to morphs reported from heterotrophic bacterial cultures, and from bacterially decomposed cyanobacterial biomass emplaced in Ca-rich media.They are also similar to CaCO3 morphs precipitated from purely inorganic solutions.

View Article: PubMed Central - PubMed

Affiliation: Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, 00-818 Warsaw, Poland. jkaz@twarda.pan.pl.

ABSTRACT
Marine cyanobacterial mats were cultured on coastal sediments (Nivå Bay, Øresund, Denmark) for over three years in a closed system. Carbonate particles formed in two different modes in the mat: (i) through precipitation of submicrometer-sized grains of Mg calcite within the mucilage near the base of living cyanobacterial layers, and (ii) through precipitation of a variety of mixed Mg calcite/aragonite morphs in layers of degraded cyanobacteria dominated by purple sulfur bacteria. The d13C values were about 2‰ heavier in carbonates from the living cyanobacterial zones as compared to those generated in the purple bacterial zones. Saturation indices calculated with respect to calcite, aragonite, and dolomite inside the mats showed extremely high values across the mat profile. Such high values were caused by high pH and high carbonate alkalinity generated within the mats in conjunction with increased concentrations of calcium and magnesium that were presumably stored in sheaths and extracellular polymer substances (EPS) of the living cyanobacteria and liberated during their post-mortem degradation. The generated CaCO3 morphs were highly similar to morphs reported from heterotrophic bacterial cultures, and from bacterially decomposed cyanobacterial biomass emplaced in Ca-rich media. They are also similar to CaCO3 morphs precipitated from purely inorganic solutions. No metabolically (enzymatically) controlled formation of particular CaCO3 morphs by heterotrophic bacteria was observed in the studied mats. The apparent alternation of in vivo and post-mortem generated calcareous layers in the studied cyanobacterial mats may explain the alternation of fine-grained (micritic) and coarse-grained (sparitic) laminae observed in modern and fossil calcareous cyanobacterial microbialites as the result of a probably similar multilayered mat organization.

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(a) Vertical cryomicrotome section of a three-year-old mat showing locations of the CaCO3-rich layers (1, 2 and 4) with indicated dominating microbiota and δ13C values. (b) X-ray diffractograms of mineral components from mat from layers l and 2: C—Mg calcite, A—aragonite, H—halite, Q—quartz (sand grains). The numbers of mat zones correspond to those shown in the diagram in Figure 4. (c) SEM-EDS spectra of elemental frequency (wt%) from dried living cyanobacterial biomass from the mat surface layer (A), micrite layer (B), and sparite layer (C).
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life-05-00744-f002: (a) Vertical cryomicrotome section of a three-year-old mat showing locations of the CaCO3-rich layers (1, 2 and 4) with indicated dominating microbiota and δ13C values. (b) X-ray diffractograms of mineral components from mat from layers l and 2: C—Mg calcite, A—aragonite, H—halite, Q—quartz (sand grains). The numbers of mat zones correspond to those shown in the diagram in Figure 4. (c) SEM-EDS spectra of elemental frequency (wt%) from dried living cyanobacterial biomass from the mat surface layer (A), micrite layer (B), and sparite layer (C).

Mentions: Stable carbon isotopes of carbonate grains from the artificial mats were analyzed at the Isotope Laboratory of the Institute of Geological Sciences PAS (Warsaw) using a Finnigan MAT Delta Plus mass spectrometer working in dual inlet mode with a universal triple collector. Carbonate precipitates from layers 1, 2 and 4 (see Figure 2a) were selected for carbon isotopic analysis. Two samples were taken from a thin dust-like layer of carbonate at the base of the living surficial cyanobacterial layer (layer 1), and four samples were taken from layers enclosing larger carbonate grains located below the dust-like carbonate layer (layers 2 and 4; Figure 2a). The fragment of the mat selected for isotopic analysis was dried using critical point drying and the carbonate layers were extracted using a scalpel under a dissecting microscope.


CaCO3 precipitation in multilayered cyanobacterial mats: clues to explain the alternation of micrite and sparite layers in calcareous stromatolites.

Kaźmierczak J, Fenchel T, Kühl M, Kempe S, Kremer B, Łącka B, Małkowski K - Life (Basel) (2015)

(a) Vertical cryomicrotome section of a three-year-old mat showing locations of the CaCO3-rich layers (1, 2 and 4) with indicated dominating microbiota and δ13C values. (b) X-ray diffractograms of mineral components from mat from layers l and 2: C—Mg calcite, A—aragonite, H—halite, Q—quartz (sand grains). The numbers of mat zones correspond to those shown in the diagram in Figure 4. (c) SEM-EDS spectra of elemental frequency (wt%) from dried living cyanobacterial biomass from the mat surface layer (A), micrite layer (B), and sparite layer (C).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390877&req=5

life-05-00744-f002: (a) Vertical cryomicrotome section of a three-year-old mat showing locations of the CaCO3-rich layers (1, 2 and 4) with indicated dominating microbiota and δ13C values. (b) X-ray diffractograms of mineral components from mat from layers l and 2: C—Mg calcite, A—aragonite, H—halite, Q—quartz (sand grains). The numbers of mat zones correspond to those shown in the diagram in Figure 4. (c) SEM-EDS spectra of elemental frequency (wt%) from dried living cyanobacterial biomass from the mat surface layer (A), micrite layer (B), and sparite layer (C).
Mentions: Stable carbon isotopes of carbonate grains from the artificial mats were analyzed at the Isotope Laboratory of the Institute of Geological Sciences PAS (Warsaw) using a Finnigan MAT Delta Plus mass spectrometer working in dual inlet mode with a universal triple collector. Carbonate precipitates from layers 1, 2 and 4 (see Figure 2a) were selected for carbon isotopic analysis. Two samples were taken from a thin dust-like layer of carbonate at the base of the living surficial cyanobacterial layer (layer 1), and four samples were taken from layers enclosing larger carbonate grains located below the dust-like carbonate layer (layers 2 and 4; Figure 2a). The fragment of the mat selected for isotopic analysis was dried using critical point drying and the carbonate layers were extracted using a scalpel under a dissecting microscope.

Bottom Line: The d13C values were about 2‰ heavier in carbonates from the living cyanobacterial zones as compared to those generated in the purple bacterial zones.The generated CaCO3 morphs were highly similar to morphs reported from heterotrophic bacterial cultures, and from bacterially decomposed cyanobacterial biomass emplaced in Ca-rich media.They are also similar to CaCO3 morphs precipitated from purely inorganic solutions.

View Article: PubMed Central - PubMed

Affiliation: Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, 00-818 Warsaw, Poland. jkaz@twarda.pan.pl.

ABSTRACT
Marine cyanobacterial mats were cultured on coastal sediments (Nivå Bay, Øresund, Denmark) for over three years in a closed system. Carbonate particles formed in two different modes in the mat: (i) through precipitation of submicrometer-sized grains of Mg calcite within the mucilage near the base of living cyanobacterial layers, and (ii) through precipitation of a variety of mixed Mg calcite/aragonite morphs in layers of degraded cyanobacteria dominated by purple sulfur bacteria. The d13C values were about 2‰ heavier in carbonates from the living cyanobacterial zones as compared to those generated in the purple bacterial zones. Saturation indices calculated with respect to calcite, aragonite, and dolomite inside the mats showed extremely high values across the mat profile. Such high values were caused by high pH and high carbonate alkalinity generated within the mats in conjunction with increased concentrations of calcium and magnesium that were presumably stored in sheaths and extracellular polymer substances (EPS) of the living cyanobacteria and liberated during their post-mortem degradation. The generated CaCO3 morphs were highly similar to morphs reported from heterotrophic bacterial cultures, and from bacterially decomposed cyanobacterial biomass emplaced in Ca-rich media. They are also similar to CaCO3 morphs precipitated from purely inorganic solutions. No metabolically (enzymatically) controlled formation of particular CaCO3 morphs by heterotrophic bacteria was observed in the studied mats. The apparent alternation of in vivo and post-mortem generated calcareous layers in the studied cyanobacterial mats may explain the alternation of fine-grained (micritic) and coarse-grained (sparitic) laminae observed in modern and fossil calcareous cyanobacterial microbialites as the result of a probably similar multilayered mat organization.

No MeSH data available.


Related in: MedlinePlus