Bio-degradation and utilization of silica and quartz

Abstract

Summary. A mesophilic bacterium, Proteus mirabilis, which was known to be able to accumulate monomer silicate ions, a thermophilic bacterium, Bacillus caldolyticus, originating from a habitat with high silica concentrations, and a silicautilizing plant, Equisetum arvense, were all found to produce monomer silica from its polymer. The monomer silica, resulting from the mineralysis of either experimentally polymerized silica, or from quartz, is taken up by P. mirabilis cells, and also by Equisetum, which then deposits the silica again as a polymer in its stem and leaves. With B. caldolyticus, which does not utilize the depolymerized product under the given cor/ditions, we found that the intensity of the minerMysis depends on the growth rate of the organism.Many investigators have demonstrated in recent years that various plants and microorganisms, including molds, diatoms and bacteria, are able to incorporate silicate ions from a silica-containing medium (Okuda and Takahashi, 1964;Yoshida et al., 1959Yoshida et al., , 1962a tIolzapfel and Engel, 1959;Lewin, 1955Lewin, , 1957Lewin et al., 1966). Most of these studies have been conducted under laboratory conditions, the silica being supplied in its monomer state. This was also the ease in our experiments on bacterial silicon metabolism (Heinen, 1962(Heinen, , 1963a(Heinen, , 1965a. In nature, however, silica scarcely occurs as a monomer, but is in the contrary mostly present in a more or less polymerized form. In most experiments on bacterial silicon metabolism this fact has so far been neglected, so that there remains a gap between the laboratory conditions and the true state given in a natural environment.There are, however, many reports that naturally occurring silica can be depolymerized and solubilized by biological action. Okuda and Takahashi (1964) for instance have shown that the concentration of monomer soluble silica in the bleeding sap exuded from cut rice stems vastly exceeds the concentration of the environment, where only high amounts of polymer silica were available. This can only be interpreted as a depolymerization process, leading to the release of monomer silica from the polymerized material. Holzapfel and Engel (1954) used quartz suspension for their experiments with molds, and reported the incorporation of monomer silica. That bacteria are also able to depolymerize crystalline silicates has been shown by Webley et al. (1960) and the release of A1, Mg, and SiO~ by fungal action from rocks has been described (Henderson and Duff, 1963). The destruction 5*

Dual Contrast Agent for Computed Tomography and Magnetic Resonance Hard Tissue Imaging

“…This indicates that also temporal degradation of the nanocomposite occurs and could allow kinetic studies with the DCA, since the contrast disappears during remodeling of the cement. The disappearance of the CT signal with time could be explained as a result of the degradation of the outer shell of the silica beads, 23,24 resulting in dilution of the gold nanoparticles. Instead, iron nanoparticles were placed on the inside of the bead, which degrade much slower.…”

Evidence for Fossilized Subsurface Microbial Communities at the TAG Hydrothermal Mound

“…Despite silici cation, the colonies retain some of their original carbon and nitrogen. Active uptake and enrichment of Si by different species of bacteria and cyanobacteria have been reported (Lauwers and Heinen 1974;Heinen and Lauwers 1988). It is possible that the Si in the low-mineralized microbes of the TAG mound may be due to biological uptake.…”

Principles of demineralization: Modern strategies for the isolation of organic frameworks

“…Studies on morphology and ultrastructure of shark enamel Reif (1973Reif ( ) 1974 ''Handbook of Histopathology and Histochemical Techniques'' is published Culling (1974Culling ( ) 1974 370 MYO devonian boring algae were described Kobluk andRisk (1974) 1974 Fungal osteoclasia: a model of bone resorption Marchiafava et al (1974Marchiafava et al ( ) 1974 Biodegradation and utilization of silica in nature Lauwers andHeinen (1974) 1975 Demineralization of bone matrix: observations using the electron microscope Thorogood andGray (1975) 1975 ''The Study of Trace Fossils'' is published Frey (1975) 1975 Mineral-tetracycline reactions and tetracycines as demineralization agents in bone, teeth and hard tissues Skinner and Nalbandian (1975); Wikesjö et al (1986); Sterrett et al (1997Sterrett et al ( ) 1975 Decalcification techniques in electron microscopy Dietrich andFontaine (1975) 1976 Isolation of 80 million year old mollusc shell proteins Weiner et al (1976Weiner et al ( ) 1976 Demineralization in forensic science Helfman and Bada (1976); Waite et al (1999Waite et al ( ) 1976 Oldest (Upper Silurian) organic remains of boring algae are found Kazmierczak andGolubic (1976) 1976 SEM study on dentin: demineralization results in shrinkage of the dentin structure Garberoglio andBrännström (1976) 1976 ''Forensic Dentistry'' is published Sopher (1976Sopher ( ) 1977 Decalcified bone as a substrate for osteogenesis Nade andBurwell (1977) 1977 Caries and the remineralization phenomena Silverstone (1977…”