Springer Handbookoƒ Marine Biotechnology Kim Editor 123 1279 58.Biomineraliz Biomineralization in Marine Organisms a Ille C. Gebeshuber 58.2.5 Example of Strontium This chapter describes biominerals and the ma- Mineralization in Various rine organisms that produce them. The proteins Marine Organisms...................... 1290 involved in biomineralization, as well as func- 58.2.6 Example of Biomineralization tions of the biomineralized structures, are treated. of the Unstable Calcium Current and future applications of bioinspired Carbonate Polymorph Vaterite .... 1290 material synthesis in engineering and medicine highlight the enormous potential of biominer- 58.3 Materials – Proteins Controlling alization in marine organisms and the status, Biomineralization................................ 1290 challenges, and prospects regarding successful 58.4 Organisms and Structures marine biotechnology. That They Biomineralize....................... 1290 58.4.1 Example: Molluscan Shells ......... 1293 58.4.2 Example: Coccolithophores......... 1293 58.1 Overview ............................................. 1279 58.1.1 Marine Biomining ..................... 1280 58.5 Functions ............................................ 1294 58.2 Materials – Biominerals 1281 ....................... 58.6 Applications ........................................ 1294 58.2.1 Biominerals Produced 58.6.1 Current Applications by Simple Precipitation of Bioinspired and Oxidation Reactions 1285 ............ Material Synthesis 58.2.2 Biological Production in Engineering and Medicine ..... 1294 of Perfectly Crystallized 58.6.2 Possible Future Applications Minerals ................................... 1285 of Bioinspired Material Synthesis 58.2.3 Composite Biomaterials ............. 1287 in Engineering and Medicine – 58.2.4 Example of Uptake Outlook .................................... 1297 and Conversion of a Very Rare Part I | 58.1 Element: Selenium .................... 1289 References................................................... 1298 58.1 Overview Marine biotechnology has huge potential across a broad ences is that better tools should be developed for the spectrum of applications, ranging from biomedicine use of marine biotechnology to help solve environmen- to the environment. However, marine biotechnology tal problems such as biofouling, pollution, ecosystem has not yet matured into an economically significant degradation, and hazards to human health. field [58.1]: This chapter gives a functional approach to biomin- eralization in marine organisms. It presents the ma- Fundamental knowledge is lacking in areas that terials that are biomineralized (which include sim- are pivotal to the commercialization of biomedi- ple precipitated minerals, biologically produced per- cal products and to the commercial application of fect crystals, and composites of minerals and an or- biotechnology to solve marine environmental prob- ganic matrix with interesting new properties) and lems, such as pollution, ecosystem disease, and the proteins that are important in biomineralization, harmful algal blooms. gives an overview of some of the thousands of ma- One of the recommendations of the 2002 report of rine organisms that produce such materials, including the Ocean Studies Board and the Board on Life Sci- information on the respective biomineralized struc- [email protected] 1280 Part I Biomedical Applications tures and their functions, and finally presents current interest to biologists and also to engineers, material sci- and possible future applications of bioinspired mate- entists, and tissue engineers. rial synthesis in engineering (including mining) and Biomineralization is characterized by interesting medicine. chemical reactions involving proteins, the creation of One of the amazing properties of biomineralization perfect crystals, the control of crystal growth and inhi- in organisms is that material, structure, and function are bition depending on the crystallographic axis, as well as strongly correlated. Biominerals are highly controlled the production of composite materials with properties in structure, composition, shape, and organization, and that are of high value to engineering. Many biolog- can yield new, more benign approaches in engineer- ical fluids are supersaturated with respect to certain ing. The complex shapes of biominerals cannot be inorganic minerals, but crystals do not form sponta- explained with simple mechanistic models of crystal neously. An example of such crystal growth inhibition growth [58.2]. is saliva; it is supersaturated with respect to hydroxya- Biotechnologists, material scientists, biologists, ge- patite formation, yet teeth do not grow continuously. ologists, engineers, and medical doctors have long been The overgrowth is prevented by phosphoprotein macro- fascinated by mineral structures in organisms. Now, molecules that bind to enamel crystals. with highly developed measurement devices at our dis- Solubility controls biomineralization. Organisms posal, we can investigate and understand biological produce hard parts by exceeding the solubility of the materials, structures, and processes, and increasingly mineral component. Increased CO2 in the oceans in- produce related bioinspired analogs [58.3]. creases carbonate mineral solubility, making biominer- Minerals are usually stiff, brittle, and cheap energy alization of calcium carbonate structures more difficult. wise. Organic materials are soft and pliable. The syn- Many of these calcium carbonate biomineralizing or- ergistic combination of both yields biominerals with ganisms are important parts of the marine food chain. amazing functionalities, with a lightweight organic The number of marine biomineralizers is vast. frame (which saves metabolic energy), filled with cheap There are 128 000 species of molluscs, 700 species of inorganic material (e.g., calcium carbonate), yielding calcareous green, red, and brown algae, more than 300 inorganic-organic hybrids (biocomposites) with well- species of deep-sea benthic foraminifera, and 200 000 defined mechanical properties [58.4]. diatom species [58.6]. Biominerals have functional structures and shapes, Biomineralization describes the formation of or- e.g., curved teeth and light baskets. The organic ma- ganized mineral structures through highly regulated trix acts as a meditator of mineralization and as crystal cellular and molecular processes. Examples of biomin- modifier. Characteristics of materials produced by con- eralized materials are enamel (97% mineral) and dentin trolled biomineralization are uniform particle sizes, (70% mineral), as well as bone (70% mineral). Crystal Part I | 58.1 well-defined structures and compositions, high levels of formation takes place in two steps: crystal nucleation spatial organization, complex morphologies, controlled (requires a high degree of saturation) and crystal growth aggregation and texture, preferential crystallographic (requires lower degree of saturation). orientation, and higher-order assembly into hierarchical structures. 58.1.1 Marine Biomining In contrast to most other biological transforma- tions, biomineralization leaves far-reaching effects on Current methods of mining are, in many cases, not the biosphere and lithosphere, including traces such as environmentally sustainable. It might be interesting bones, shells, and fossils, but also mountain ranges and to focus on bio-assisted ways of obtaining resources cliffs [58.5]. Biomineralization has implications on the such as Fe, Al, and Ti from marine environments global scale, via the Earth sciences. It is important in (Table 58.1) [58.7]. All kinds of microbes contribute the global cycling of elements, in sedimentology, in actively to geological phenomena, and central to many fossilization (paleontology and taxonomy), in marine such geomicrobial processes are transformations of chemistry, and in geochemistry [58.4]. metals and minerals. Bioremediation is the use of bi- In the course of biomineralization, mineral products ological systems for the clean-up of organic and in- (biominerals) are created in organisms. Biomineraliza- organic pollution, with bacteria and fungi being the tion has been around since the first Prokaryota appeared most important organisms for reclamation, immobi- in the Archaean, the geological aeon from about 4 lization, or detoxification of metallic and radionuclide to 2.5 billion years ago. Biomineralization is of high pollutants [58.8]. [email protected] Biomineralization in Marine Organisms 58.2 Materials – Biominerals 1281 Table 58.1 Concentration of transition metals and zinc in eral-sulfide-oxidizing bacteria. Sulfurivirga caldicuralii seawater (after [58.11], original references after [58.12– is a microaerobic, thermophilic, thiosulfate-oxidizing 14]) chemolithoautotroph that is related to pyrite, arseni- Element Seawater (M) 108 cal pyrite, and chalcopyrite. The archaea Sulfolobus shibitae, Metallosphaera Acidianus infernus Fe 0.005–2 sp. and are related to chalcopyrite [58.18]. Zn 8.0 Cu 1.0 In low-temperature, aqueous habitats with oxygen, Mo 10.0 bacteria can affect the dissolution or precipitation Co 0.7 of minerals through their reduction or oxidation of Cr 0.4 compounds containing Mn, Fe, S, C, U, Cu, Mo, Hg, V 4.0 and Cr [58.10, p. 306]. Mn 0.7 Ni 0.5 Certain organisms are involved in the deposition of marine minerals, e.g., bacteria in deep-sea polymetal- Biomining is the use of microorganisms and plants lic nodules and coccoliths in seamount crusts [58.19]. (phytomining) to aid