Mineralization (biology)

In biology, mineralization refers to a process where an inorganic substance precipitates in an organic matrix. This may be due to normal biological processes that take place during the life of an organism such as the formation of bones, egg shells, teeth, coral, and other exoskeletons. This term may also refer to abnormal processes that result in kidney and gall stones.

IUPAC Definition
Process through which an organic substance becomes impregnated by or turned
into inorganic substances.

Note 1: A particular case is the process by which living organisms produce and
structure minerals often to harden or stiffen existing tissues. (See biomineralization.)

Note 2: In the case of polymer biodegradation, this term is used to reflect conversion
to CO2 and H2O and other inorganics. CH4 can be considered as part of the mineralization
process because it comes up in parallel to the minerals in anaerobic composting, also
called methanization.[1][2]

Types of mineralization

Mineralization can be subdivided into different categories depending on the following: the organisms or processes that create chemical conditions necessary for mineral formation, the origin of the substrate at the site of mineral precipitation, and the degree of control that the substrate has on crystal morphology, composition, and growth.[3] These subcategories include: biomineralization, organomineralization, and inorganic mineralization, which can be subdivided further. However, usage of these terms vary widely in scientific literature because there are no standardized definitions. The following definitions are based largely on a paper written by Dupraz et al. (2009), which provided a framework for differentiating these terms.

Biomineralization

Biomineralization, biologically-controlled mineralization, occurs when crystal morphology, growth, composition, and location is completely controlled by the cellular processes of a specific organism. Examples include the shells of invertebrates, such as molluscs and brachiopods. Additionally, mineralization of collagen provides the crucial compressive strength for the bones, cartilage, and teeth of vertebrates.[4]

Organomineralization

This type of mineralization includes both biologically-induced mineralization and biologically-influenced mineralization.

  • Biologically-induced mineralization occurs when the metabolic activity of microbes (e.g. bacteria) produces chemical conditions favorable for mineral formation. The substrate for mineral growth is the organic matrix, secreted by the microbial community, and affects crystal morphology and composition. Examples of this type of mineralization include calcareous or siliceous stromatolites and other microbial mats. A more specific type of biologically-induced mineralization, remote calcification or remote mineralization, takes place when calcifying microbes occupy a shell secreting organism and alter the chemical environment surrounding the area of shell formation. The result is mineral formation not strongly controlled by the cellular processes of the metazoan host (i.e. remote mineralization), and may lead to unique or unusual crystal morphologies.[5]
  • Biologically-influenced mineralization takes place when chemical conditions surrounding the site of mineral formation are influenced by abiotic processes (e.g. evaporation or degassing). However, the organic matrix (secreted by microorganisms) is responsible for crystal morphology and composition. Examples include micro- to nano-meter scale crystals of various morphologies.

Inorganic mineralization

Inorganic mineralization is a completely abiotic process. Chemical conditions necessary for mineral formation develop via environmental processes, such as evaporation or degassing. Furthermore, the substrate for mineral deposition is abiotic (i.e. contains no organic compounds) and there is no control on crystal morphology or composition. Examples of this type of mineralization include cave formations, such as stalagmites and stalactites.

Biological mineralization can also take place as a result of fossilization. See also calcification.

Bone mineralization occurs in human body by cells called osteoblasts.

References
  1. "European Committee for Standardization". Plastics – Guide for Vocabulary in the Field of Degradable and Biodegradable Polymers and Plastic Items. 2006.
  2. Vert, Michel; Doi, Yoshiharu; Hellwich, Karl-Heinz; Hess, Michael; Hodge, Philip; Kubisa, Przemyslaw; Rinaudo, Marguerite; Schué, François (2012). "Terminology for biorelated polymers and applications (IUPAC Recommendations 2012)" (PDF). Pure and Applied Chemistry. 84 (2): 377–410. doi:10.1351/PAC-REC-10-12-04.
  3. Dupraz, Christophe; Reid, R. Pamela; Braissant, Olivier; Decho, Alan W.; Norman, R. Sean; Visscher, Pieter T. (2009-10-01). "Processes of carbonate precipitation in modern microbial mats". Earth-Science Reviews. Microbial Mats in Earth's Fossil Record of Life: Geobiology. 96 (3): 141–162. doi:10.1016/j.earscirev.2008.10.005.
  4. Sherman, Vincent R. (2015). "The materials science of collagen". Journal of the Mechanical Behavior of Biomedical Materials. 52: 22–50. doi:10.1016/j.jmbbm.2015.05.023. PMID 26144973.
  5. Vermeij, Geerat J. (2013-09-27). "The oyster enigma variations: a hypothesis of microbial calcification". Paleobiology. 40 (1): 1–13. doi:10.1666/13002. ISSN 0094-8373.


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