水面に短時間で発生する鉄生体鉱物の薄膜

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Biofilms quickly occur on the water surface, associated with Fe-bacteria, such as Leptothrix sp., Gallionella sp. and Toxothrix sp. are the most common pioneering species in microbial communities. The bacterial colonies form, Fe-rich biofilms within a few days which is active oxic zone of the top water surface. Biofilms are composed of amorphous iron hydroxides, goethite, ferrihydrite and schwertmannite Fe_8O_8(OH)_6SO_4 (2.5 and 1.5 Å) are found both in natural system and cultured solution. SEM-EDX, TEM and atomic-force microscopy showed the formation processes of Fe-rich biofilms with sub-micron rugged structure on the primitive stage. In this paper biomineral structure of Fe-rich biofilms collected from underground water at three places was described. The structure is affected by the water physical and chemical environment (anaerobic or oxidized condition), bacterial species, water chemical composition, and species interactions. The old idea of the biofilms is simply microbes suspended in a homogeneous, but in this study variety of microorganisms with Fe-rich cell was revealed. Brownish black biofilms grow on the surface of underground water in the Kakuma Campus of Kanazawa University, are of predominantly iron oxidizing bacteria, such as Leptothrix sp., Gallionella sp. and Toxothrix sp.. The biofilms use ferrous ions as their energy source through the oxidation into ferric ions. TEM of the biofilms have revealed mucoid substances of bacteria, like polysaccharides are effective for adhesion of iron hydroxides produced through biomineralization of various bacterial communities. The quick condensation process of ordered iron bacterial colonies considered to be a factor for increasing the thickness of biofilms. This is the first time oriented Fe-bacterial sheet / nets in the colonies have been found in biofilms within a few days aging time. The formation mechanism of biofilms on the water surface can be apply science to implants to be placed in the human body in biomedical applications, such as catheter, heartlung machine, and contact lenses.
日本粘土学会の論文
2002-08-24

水面に短時間で発生する鉄生体鉱物の薄膜

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