title: Magnesium-Calcite Crystal Formation Mediated by the Thermophilic Bacterium Geobacillus thermoglucosidasius Requires Calcium and Endospores.
abstract: Fresh Geobacillus thermoglucosidasius cells grown on soybean-casein digest nutrient agar were inoculated as a parent colony 1 cm in diameter on the surface of an agar gel containing acetate and calcium ions (calcite-promoting hydrogel) and incubated at 60 °C for 4 days, after which magnesium-calcite single crystals of 50-130 µm in size formed within the parent colony. Addition of EDTA, polyacrylic acid or N,N-dicyclohexylcarbodiimide to the calcite-forming hydrogel inhibited the parent colony from forming magnesium-calcite crystals. Inoculation of G. thermoglucosidasius on calcite-forming hydrogel containing 5 µM cadmium and 20 µM zinc resulted in a decrease in the sporulation rate from 55 to 7-8 %. Magnesium-calcite synthesis decreased relative to the sporulation rate. G. thermoglucosidasius exhibited higher adsorption/absorbance of calcium than other Geobacillus sp. that do not mediate calcite formation and higher levels of magnesium accumulation. Calcium ions contained in the calcite-promoting hydrogel and magnesium ions concentrated in G. thermoglucosidasius cells serve as the elements for magnesium-calcite synthesis. The observed decreases in sporulation rate and magnesium-calcite formation support the hypothesis that endospores act as nuclei for the synthesis of magnesium-calcite single crystals.
authors: Department of Biochemistry and Applied Biosciences, University of Miyazaki, 1-1 Gakuen Kibanadai-Nishi, Miyazaki, 889-2192, Japan.
authors: Rie
authors: R
authors: Murai
authors: Department of Biochemistry and Applied Biosciences, University of Miyazaki, 1-1 Gakuen Kibanadai-Nishi, Miyazaki, 889-2192, Japan. a04109u@cc.miyazaki-u.ac.jp.
authors: Naoto
authors: N
authors: Yoshida
mesh_terms: D002118:Calcium / Q000378:metabolism*; D002119:Calcium Carbonate / Q000378:metabolism*; D056506:Geobacillus / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism*; D006358:Hot Temperature; D008274:Magnesium / Q000378:metabolism*; D013171:Spores, Bacterial / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism
chemical_list: D002119:Calcium Carbonate; D008274:Magnesium; D002118:Calcium