Precipitation and characterization of CaCO3 of Bacillus amyloliquefaciens U17 strain producing urease and carbonic anhydrase.

In the present study, the properties of calcium carbonate mineralization and urease and carbonic anhydrase activities of Bacillus amyloliquefaciens U17 isolated from calcareous soil of Denizli (Turkey) were analyzed. CaCO3 was produced in all growth phases. Strain U17 showed 0.615 ± 0.092 µmol/min/mg urease enzyme activity in calcium mineralization medium and 1.315 ± 0.021 µmol/min/mg urease enzyme activity in Luria-Bertani medium supplemented with urea, whereas it showed 36.03 ± 5.48 nmol/min/mg carbonic anhydrase enzyme activity in CaCO3 precipitation medium and 28.82 ± 3.31 nmol/min/mg carbonic anhydrase enzyme activity in Luria-Bertani medium supplemented with urea. The urease B protein expression level of strain U17 was detected by western blotting for the first time. The produced CaCO3 crystals were analyzed by X-ray diffraction, X-ray fluorescence, confocal RAMAN spectrophotometer, scanning electron microscopy, and electron probe microanalyzer for the evaluation of their morphological and elemental properties. Rhombohedral vaterite and layered calcite crystals were clearly detected and verified by mineralogical analyses. All these results showed that strain U17 can be used in many engineering and geological applications due to its CaCO3 precipitation ability.