BIOCHEMICAL EFFECTS OF THE UNICELLULAR GREEN ALGA CHLORELLA VULGARIS ON THE PRECIPITATION RATES AND POLYMORPHISM OF CALCIUM CARBONATE MINERALS

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概要

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• Photosynthetic microbes play an important role in the formation of calcium carbonate minerals in the various earth's surface environments. To evaluate the effects of photosynthetic microbes on the precipitation rates and polymorphism, precipitation experiments were performed in systems with and without unicellular green alga Chlorella vulgaris. The experiments were conducted by the batch method using 100ml solutions containing 5.0mM CaCl_2, 20.0mM NaHCO_3, and 0.0, 1.0, 2.0, 3.0, 4.0, or 5.0mM MgCl_2 at 25℃ for 10 days. Three types of reaction systems were prepared: (1) abiotic system containing no C. vulgaris, (2) biotic system containing 10^6 cells/ml of C. vulgaris under light condition, and (3) biotic system containing 10^6 cells/ml of C. vulgaris under dark condition. Throughout the reaction period, solution pH, concentrations of Ca^<2+>, Mg^<2+>, and HCO_3^- ions, and dissolved polysaccharides and proteins released from C. vulgaris cells were measured daily. The results indicated that C. vulgaris enhanced precipitation rates by approximately 2.7-2.9 times under light condition as compared with those of the abiotic system, which was due to increase in solution pH mainly through the algal photosynthetic activity. In contrast, C. vulgaris slightly inhibited the precipitation rates under dark condition by the interactions of extracellular polysaccharides with the surface of CaCO_3 precipitates. In addition, C. vulgaris inhibited the formation of aragonite and favored calcite formation as the dominant polymorph despite the presence of Mg^<2+> ions. This may be attributed to the greater adsorption affinity of the polysaccharides for the surface of aragonite than for the calcite surface.

著者

• KAWANO MOTOHARU

  Graduate School of Science and Engineering, Kagoshima University

• HWANG JINYEON

  Division of Earth Environmental System, Pusan National University

• Hwang Jinyeon

  Division Of Earth Environmental System Pusan National University

• Kawano Motoharu

  Graduate School Of Science And Engineering Kagoshima University

関連論文

• INFLUENCE OF GRAM-NEGATIVE BACTERIUM PSEUDOMONAS FLUORESCENS ON THE PRECIPITATION RATES AND POLYMORPHISM OF CALCIUM CARBONATE MINERALS
• BIOCHEMICAL EFFECTS OF THE UNICELLULAR GREEN ALGA CHLORELLA VULGARIS ON THE PRECIPITATION RATES AND POLYMORPHISM OF CALCIUM CARBONATE MINERALS
• EFFECT OF ORGANIC ACIDS ON THE PRECIPITATION RATE AND POLYMORPHISM OF CALCIUM CARBONATE MINERALS IN SOLUTIONS WITH Mg^ IONS

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