Biomineralisation

Abb. 1: The green algae Scenedesmus
obliquus
(light microscopy).

Living organisms produce inorganic materials by biomineralization processes. Two different mechanisms are known: a) biologically induced and b) biologically controlled biomineralization. The main difference between the two mechanisms is the active control of the process by the organism at b), resulting in homogenous shapes and structures.

Abb. 2:The coccolithophore Emiliania
huxleyi
generates intracellular calcite
coccoliths (SEM).
Abb. 4:Four S. obliquus cells with an
aragonite crystal, mineralized in
zinc-containing medium (SEM).
Abb. 3: Intracellular zinc-phosphate needles
formed due to detoxification of zinc
containing medium. Cross section of a
S. obliquus
cell (Inset). (TEM).

We are aiming the production of technical relevant ceramic materials by living microalgae. Two different single-cellular algae species are used for the approach. The green algae Scenedesmus obliquus (Fig. 1) forms inorganic materials by biologically induced mineralization process. The second species is the marine coccolithophore Emiliania huxleyi (Fig. 2) which mineralizes highly structured calcite plates (coccoliths) intracellular by a biologically controlled mineralization process. The algae are cultured in media containing non-biogenic ions, like zinc. Since zinc is toxic in high amounts the algae take up the zinc ions in order to detoxify the medium. Intracellular, the zinc ions are bound to organic molecules to form non-toxic complexes. We demonstrated that Scenedesmus obliquus detoxify the cytoplasm by the formation of zinc-phosphate based nano-needles (Fig. 3). Zinc-phosphates are technically applied as anticorrosive or cement in dental applications.

The biologically induced mineralization of calcium carbonate by S. obliquus is also investigated at the department. We showed, that in the presence of zinc S. obliquus induces the mineralization of aragonite and not the calcite polymorph, which is mineralized in aqueous media without zinc (Fig. 4).

The second species Emiliania huxleyi is also cultivated in media containing non-biogenic ions. Also, these ions are transported inside the cell. We are aiming the incorporation of these ions into the coccoliths.

Abb. 5: Mineralization of CaCO3 by Halomonas halophila, halophilic bacteria strain.

Beside algae, the halophilic bacteria Halomonas halophila induces the mineralization of calcium carbonate under appropriate conditions. The natural mineralization process and modified mineralization processes for the formation of various inorganic compounds are under investigation. The bacteria form organic-inorganic hybrid materials and can be applied for wastewater remediation of metal ion pollutions. Thereby, metal ions are immobilized on the bacterial surface and are buried in a CaCO3 layer in a second step.



Projects:

DFG PAK 410: Biologische Erzeugung von Oxidkeramiken http://www.bionik.uni-stuttgart.de
BI469/15-1
In vitro und in vivo Synthesen von Oxidkeramiken

Literature:

Kanold, J. M., Lemloh, M.-L., Schwendt, P., Burghard, Z., Baier, J., Herbst, F., Bill, J, Marin, F., Brümmer, F. (in press). In vivo enrichment of magnesium ions modifies sea urchin spicule properties. Bioinspired, Biomimetic and Nanobiomaterials, DOI: 10.1680/bbn.14.00023

Lemloh, M.-L., Marin, F., Herbst, F., Plasseraud, L., Schweikert, M., Baier, J., Bill, J., Brümmer, F., 2013. Genesis of amorphous calcium carbonate containing alveolar plates in the ciliate Coleps hirtus (Ciliophora, Prostomatea). Journal of Structural Biology 181, 155-161.

Rothenstein, D., Baier, J., Schreiber, T.D., Barucha, V. and Bill, J., 2012. Influence of zinc on the calcium carbonate biomineralization of Halomonas halophila. Aquatic Biosystems 2012, 8:31. Link

Santomauro, G., Baier, J., Huang, W., Pezold, S., Bill, J., 2012a. Formation of Calcium Carbonate Polymorphs Induced by Living Microalgae. Journal of Biomaterials and Nanobiotechnology 3, 413-420. Link

Santomauro, G., Srot, V., Bussmann, B., van Aken, P.A., Brümmer, F., Strunk, H., Bill, J., 2012b. Biominerlization of zinc-phosphate-based nano needles by living micoralgea. Journal of Biomaterials and Nanobiotechnology, 3, 362-370. Link