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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.

No MeSH data available.


Related in: MedlinePlus

Diagram showing a variety of CaCO3 morphs precipitated under controlled conditions from a solution of different pH and [polymer]/[CaCO3] ratio for which the unit for both concentrations is g L−1. Arrows indicate morphologies observed simultaneously. Morphs obtained from the same system are drawn in gray and those from other experiments are drawn in black (from [58], slightly modified).
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life-05-00744-f007: Diagram showing a variety of CaCO3 morphs precipitated under controlled conditions from a solution of different pH and [polymer]/[CaCO3] ratio for which the unit for both concentrations is g L−1. Arrows indicate morphologies observed simultaneously. Morphs obtained from the same system are drawn in gray and those from other experiments are drawn in black (from [58], slightly modified).

Mentions: Bacterial mediation has been suggested in studies on CaCO3 precipitates obtained from cyanobacterial mats decaying in calcium-rich solutions [96,97,101,102]. The morphologies of the CaCO3 particles from these experiments are strikingly similar, if not identical, to the spectrum of morphs generated in our mats. Spheres, hemispheres, dumbbells, and peanut-shaped particles have also been produced in cultures of heterotrophic bacteria growing in CaCO3-supersaturated solutions with and without addition of Mg (e.g., [103,104,105,106,107,108,109,110]). However, none of these studies provided unequivocal evidence for a metabolically active role of bacteria in the precipitation of the morphs. Moreover, a whole array of CaCO3 morphs has been obtained from inorganic solutions after the controlled addition of various polymers [57,58,111,112,113,114,115,116,117,118,119,120,121] It seems therefore that the role of heterotrophic bacteria in the process of CaCO3 precipitation is mainly to supply the calcium-carbonate-oversaturated medium with polymers effective in crystallization control of the final morphologies (morphs) of the CaCO3 particles (Figure 7).


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)

Diagram showing a variety of CaCO3 morphs precipitated under controlled conditions from a solution of different pH and [polymer]/[CaCO3] ratio for which the unit for both concentrations is g L−1. Arrows indicate morphologies observed simultaneously. Morphs obtained from the same system are drawn in gray and those from other experiments are drawn in black (from [58], slightly modified).
© Copyright Policy
Related In: Results  -  Collection

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

life-05-00744-f007: Diagram showing a variety of CaCO3 morphs precipitated under controlled conditions from a solution of different pH and [polymer]/[CaCO3] ratio for which the unit for both concentrations is g L−1. Arrows indicate morphologies observed simultaneously. Morphs obtained from the same system are drawn in gray and those from other experiments are drawn in black (from [58], slightly modified).
Mentions: Bacterial mediation has been suggested in studies on CaCO3 precipitates obtained from cyanobacterial mats decaying in calcium-rich solutions [96,97,101,102]. The morphologies of the CaCO3 particles from these experiments are strikingly similar, if not identical, to the spectrum of morphs generated in our mats. Spheres, hemispheres, dumbbells, and peanut-shaped particles have also been produced in cultures of heterotrophic bacteria growing in CaCO3-supersaturated solutions with and without addition of Mg (e.g., [103,104,105,106,107,108,109,110]). However, none of these studies provided unequivocal evidence for a metabolically active role of bacteria in the precipitation of the morphs. Moreover, a whole array of CaCO3 morphs has been obtained from inorganic solutions after the controlled addition of various polymers [57,58,111,112,113,114,115,116,117,118,119,120,121] It seems therefore that the role of heterotrophic bacteria in the process of CaCO3 precipitation is mainly to supply the calcium-carbonate-oversaturated medium with polymers effective in crystallization control of the final morphologies (morphs) of the CaCO3 particles (Figure 7).

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