EXTREMÓFILOS, BIODIVERSIDAD, FISIOLOGÍA, BIOQUÍMICA, BIOLOGÍA MOLECULAR, ECOLOGÍA Y BIOTECNOLOGÍA

Abstract

Organic mineralization is a process by some eukaryotic or prokaryotic cells produces minerals. Through this mechanism, about 60 different minerals has been identified. Bacillus subtilis, is a bacterium that induces the precipitation of calcium carbonate crystals (CaCO3), in low Ca2+ conditions (< 20 mM). Therefore, this bacterium is a great model for biotechnological, geo-technological, paleobiology and civil engineering applications. The most recent is its implementation for soil strengthening, CO2 sequestration, heavy metal removal and bio-cementation. The main of this work is characterize the calcium carbonate (CaCO3) composite produced by B. subtilis at high calcium acetate (CA) concentration. The cells 1x108 cells/ml were grown by 6 days in nutrient agar, supplemented with CA. Scanning electron microscopy analysis showed calcite-like morphologies with 10, 50 and 100 mM CA; while, characteristic spherical structures of vaterite were formed with 250 and 500 mM CA. Changes in the proportions of calcite and vaterite formed in relation to the concentration of CA were confirmed by X-ray diffraction. The highest calcite production was obtained with 10 mM and 50 mM CA (100 %). An incipient production of vaterite (0.9 %) was observed from 100 mM CA, which increased with respect to the amount of CA (54.1 % and 94.9 % with 250 mM and 500 mM, respectively). These results indicate that the mineralization of CaCO3 crystals induced and influenced by B. subtilis depends on the concentration of the calcium-coupled carbon source.