Magnetite Biomineralization: Occurrence, and Crystallography - Research Paper Example

Magnetite Biomineralization Magnetite Fe3O4 is a naturally occurring mineral that is also found in animal tissues. Sofar, scientists note that roughly 60 naturally occurring minerals are precipitated by living organisms. In living organisms, magnetite is formed through the process of biomineralization. Biomineralization began roughly 3500 million years ago and is a common phenomenon among living organisms today. Magnetite is precipitated by protists, bacteria, humans, and a number of animals. In humans, deposits of magnetite have been found in different brain tissues. A recent study showed that most human brain tissues had a least five million single domain crystals per gram and in excess of 100 million crystals per for dura and pia. The crystals were in clumps of 50-100 particles. During biologically controlled mineralization of magnetite the organism makes use of cell activities to control the nucleation, growth, final place of deposit, and the morphology of the mineral. The process of biomineralization of magnetite commonly occurs in an isolated environment. The nucleation and growth of biominerals is dependent on the existence of a localized zone that enjoys and maintains adequate supersaturation. The two phases of iron that commonly feature in the process of magnetite biomineralization in bacteria are ferrihydrite and magnetite. In bacteria, magnetosome organelle is responsible for producing magnetite. The organelle is basically a biomineralized greigite or magnetite. The Biomineralization of Magnetite Introduction Magnetite Fe3O4 is a naturally occurring mineral. Scientists note that the mineral is one of the most magnetic minerals that naturally occur on earth. Research has shown that magnetite does not only occur naturally on the earth, it is also found in animal tissues. Indeed scientists note that almost all groups of organisms form one form or another of biominerals. Some of the organisms that have been found to precipitate magnetite include arthropods, chordates, and mollusks. Recent studies show that biominerals are found in humans such as in bones and teeth. The precipitation of magnetite in living organisms occurs through the biomineralisation process. This paper will discuss Magnetite biomineralization in light of its chemistry, occurrence, and crystallography among other issues. Overview of Biomineralization Biomineralisation or biologically regulated mineralization is basically the process through which living organisms produce minerals according to Kirschvink and Hagadorn (2000). Weiner and Dove (2013) note that biomineral products are composites that comprise both organic and mineral components. While biominerals closely resemble their inorganic counterparts, they often have unusual morphologies as noted by Weiner and Dove (2013). Another main characteristic of biominerals is that they are usually composite materials or collections of crystals separated by organic materials. According to Gordon Research Conferences (2014), biomineralisation began well over 500 million years ago, during the pre-Cambrian period. In their article, Weiner and Dove (2013) give an overview of the biomineralization processes. The researchers note that roughly 3500 or so million years ago, prokaryotes and eukaryotes developed the ability to form minerals. Many other organisms from different phyla have henceforth developed the ability to produce many of the known minerals. The process of forming biominerals regularly occurs under controlled conditions to the extent that the biomineral phases often are associated with specific size, shapes, trace and isotopic element composition and crystallinity (Boskey, 2003). In this sense biominerals differ from their inorganically formed counterparts. Studies show that calcium is a preferred cation for most organisms during the formation of biominerals. No wonder close to half of the known biominerals bear calcium as part of their compositions. Close to 25% of the known biominerals are amorphous to the extent that they do not cause x-rays to diffract. Some biominerals include amorphous silica, amorphous hydrous iron phosphate, and calcium carbonate minerals. Figure 1 shows amorphous hydrous iron phosphate granules deposited in the holothurians, Molpadia. Fig 1: Amorphous hydrous iron phosphate granules deposited in the holothurians, Molpadia. Courtesy of Weiner and Dove (2013). According to Weiner and Dove (2013), the nucleation and growth of biominerals is dependent on the existence of a localized zone that enjoys and maintains adequate supersaturation. Many biological systems have the sites in which minerals are deposited isolated from the environment by a geometry that is physically delimiting. The compartment in which biomineralization occurs can be of any size but must have the capacity to alter the activity of one or more constituent(s); more often than not, the cation; protons and, sometimes, ions (Weiner and Dove, 2013). Any fluxes in the chemistry of ions must, however, meet one condition, the electroneutrality of the fluid must be maintained as noted by Weiner and Dove (2013). Meanwhile, the supply or removal of ions can be done through one of two means; passive diffusion gradients or active pumping by organelles. Worth noting is that the chemical compositions of the in vivo fluids that feature around or at the site in which the biomineral is formed has a direct impact on the mineralization process (Weiner and Dove, 2013). Table 1 gives a comparison between average freshwater and sea water solute compositions which can also be compared to the compositions of many typical biological fluids. Table 1: Summary of the compositions of natural waters and biological fluids Courtesy of Weiner and Dove (2013) The Biomineralization of Magnetite Biominerals occur almost everywhere in the world. So far, scientists have established more sixty biominerals that occur in nature. One of the biominerals that occur in nature as previously noted is magnetite. Researchers note that the processes of biomineralization can be grouped into two main categories depending on the level of biological control as noted by Addadi and Weiner (1992). The groups include biologically induced and biologically controlled. When secondary precipitation of minerals occurs as a consequence of the interactions between the environment and biological activities, biologically induced mineralization applies. In this case, the biological system enjoys little control with respect to the habit and type of mineral deposited in as much as it continues to control such factors as pH, and the compositions of secretions among others. The biologically formed minerals that result from these processes are generally heterogeneous. Biologically controlled mineralization on the other hand occurs when the organism makes use of cell activities to control the nucleation, growth, final place of deposit, and the morphology of the mineral as noted by Lenders, Altan, Bomans, Arakaki, Bucak, With et al. (2014). This kind of mineralization commonly occurs in an isolated environment. Characteristics of minerals precipitated through biologically controlled mineralization include: uniform particle size, complex morphologies, preferential crystallographic orientation, ordering into hierarchical structures, and high level of organization spatially. As will be realized in the following section, the biomineralization of magnetite in humans and magnetostatic bacteria is often biologically controlled. According to Kirschvink, Kobayashi-Kirschvink, and Woodford (1992), magnetite is precipitated by protists, bacteria and a number of animals. In their study involving analysis of brain tissues using electron diffraction, high-resolution transmission electron microscopy, element analysis, and ultrasensitive superconducting magnetometer, Kirschvink, Kobayashi-Kirschvink, and Woodford (1992) established that the human brain contains some level of biogenic magnetite. The study revealed the presence of minerals in the magnetite-maghemite family whose structures and crystal morphologies significantly resembled those produced by fish and magnetotatic bacteria. Findings of the study showed that most brain tissues had a least five million single domain crystals per gram. Furthermore, the findings of the study showed that most of the tissues had more than 100 million crystals per for dura and pia. The crystals as noted by Kirschvink, Kobayashi-Kirschvink, and Woodford (1992) were in clumps of 50-100 particles. Figure 2 shows the crystal structure of magnetite. Fig2. : Crystal structure of magnetite Courtesy of www.nature.com Siponen, Legrand, Widdrat, Jones, Zhang, Chang et al. note that magnetotatic bacteria use the magnetosome organelle to align with the magnetic field of the earth. The organelle is basically a biomineralized greigite (Fe (II)Fe(III)2S4) or magnetite (Fe(II)Fe(III)2O4) crystal that is entrenched in a lipid vesicle. According to a study by the researchers, the magnetochrone plays a vital role in biomenralisation in magnetotactic bacteria. An analysis of the structure of the magnetosome-associated protein (MamP) reveals that it is an iron oxidase that has a part to play in the formation of iron three ferrihydrite that is a requirement for the growth of magnetite crystal in vivo. Baumgartner and Faivre (2011) note that the magnetic crystals that are found in the magnosomes of magnetotatic beacteria exhibit strain and species specific morphology and size. They are highly optimized, forming chains within the cells of the bacteria enabling the bacteria to navigate as they act as magnetic field actuators. Figures 3a and b show the structure of a magnetochrome domain while figures 4 a and b show the overall structure of MamP homodimer. Fig 3: Structure of a magnetochrome domain Courtesy of www.nature.com Fig 4: Overall structure of MamP homodimer. Courtesy of www.nature.com The findings by Siponen et al. regarding how magnetite is formed in magnetostatic bacteria augers well with the findings of Fdez-Gubieda, Muela, Alonso, García-Prieto, Olivi Luca, Fernández-Pacheco et al (2013). In their research, Fdez-Gubieda et al. established that two phases of iron are involved in the biomineralisation process. The two phases are ferrihydrite and magnetite. The first step involved in the magnetite biomineralization in M. gryphiswaldense involves the accumulation of iron in the form of ferrihydrite. The second step in the same respect involves the rapid biomineralization of magnetite from ferrihydrite, which confirms that important role of ferrihydrite as a source of iron ions for the biomineralization process. According to Fdez-Gubieda et al. (2013), bacterial ferritin cores could be the place of origin of the ferhydrite. These cores are characteristically high in phosphorus and have a poor crystalline structure. Conclusion In conclusion, several organisms across all phyla precipitate or produce biominerals. While some biominerals are biologically induced, others are biologically controlled. The mineralization of magnetite in humans and bacteria is more often than not biologically controlled as opposed to being biologically induced. The nucleation and growth of biominerals is often dependent on the existence of a localized zone that is supersaturated. The precipitation of magnetite in humans and bacteria in this respect is associated with specific functions. In bacteria, for example, it serves to help the organisms align to the earth’s magnetic field, which helps in navigation. Iron oxidase and ferritin appear to be the source materials for the magnetite precipitated by bacteria. Studies indicate the presence of biomineralised magnetite in human brain tissues. Some of the resources that are used in the production of magnetite in bacteria include magnetosome organelles and ferritine core. References ADDADI, L. and S. WEINER (1992) Control and Design Principles in Biological Mineralization. Angewandte Chemie International Edition in English vol. 31, no. 2, pp.153–169. BAUMGARTNER, J. AND FAIVRE, D. Magnetite Biomineralization in Bacteria. Molecular Biomineralization. Progress in Molecular and Subcellular Biology 52. 2011, pp 3-27. Date: 26 Jul 2011 BOSKEY, A.L. (2003). Biomineralization: An overview. Connective Tissue Research 44 Supplement 1, pp. 5–9. FDEZ-GUBIEDA M. LUISA, M., ALONSO J., GARCÍA-PRIETO A., OLIVI L., FERNÁNDEZ-PACHECO R and BARANDIARÁN J. (2013) Magnetite Biomineralization in Magnetospirillum gryphiswaldense: Time-Resolved Magnetic and Structural Studies. ACS Nano, Vol. 7 no. 4, pp. 3297–3305 DOI: 10.1021/nn3059983. GORDON RESEARCH CONFERENCES (2014) Biomineralization: Where Geology Meets Biology: The Inorganic-Organic Interface http://www.grc.org/programs.aspx?year=2014andprogram=biomin KIRSCHVINK J L., KOBAYASHI-KIRSCHVINK A., and WOODFORD B. J. (1992) Magnetite biomineralization in the human brain. Proc Natl Acad Sci U S A. Vol. 89, no. 16, pp. 7683–7687. PMCID: PMC49775 KIRSCHVINK J.L. AND HAGADORN, J.W. (2000) A Grand Unified theory of Biomineralization. In Buerlein, E., ed., The Biomineralisation of Nano- and Micro-Structures, Wiley-VCH Verlag GmbH, Weinheim, Germany, pp. 139-150, LENDERS J. , ALTAN C., BOMANS P., ARAKAKI A., BUCAK S., WITH G. AND SOMMERDIJK N. (2014). A Bioinspired Coprecipitation Method for the Controlled Synthesis of Magnetite Nanoparticles. Crystal Growth and Design, Vol. 14 , no. 5561-5568. SIPONEN M. I., LEGRAND P., WIDDRAT M., JONES S. R., ZHANG W. J., CHANG M. C., FAIVRE D., ARNOUX ., and PIGNOL D. (2013) Structural insight into magnetochrome-mediated magnetite biomineralization. Nature. Vol. 502 No. 7473, pp.681-4. doi: 10.1038/nature12573. WEINER S. and DOVE P. M. (2013). An Overview of Biomineralization Processes and the Problem of the Vital Effect. www.google.com/url?sa=tandrct=jandq=andesrc=sandsource=webandcd=7andcad=rjaanduact=8andved=0CEgQFjAGandurl=http%3A%2F%2Feps.mcgill.ca%2F~jeannep%2Feps%2FEPSC644%2FWeiner%2520and%2520Dove%2520Overview%2520Biomineralization.pdfandei=-lZmVMG8HuWgyAO3oIHYDgandusg=AFQjCNFyD4WaCH1CWiIzb7RlZL_ua12r7wandsig2=A_-f6_KNjZ66WyY2NWTJfwandbvm=bv.79142246,d.bGQ List of figures Fig 1: Amorphous hydrous iron phosphate granules deposited in the holothurians, Molpadia. Fig 3: Structure of a magnetochrome domain Courtesy of www.nature.com Fig2. : Crystal structure of magnetite. Courtesy of www.nature.com Fig 4: Overall structure of MamP homodimer. Courtesy of www.nature.com List of Tables Table 1: Summary of the compositions of natural waters and biological fluids Read More

 

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