Calcium carbonate precipitation induced by ureolytic bacteria Bacillus licheniformis

In this study, we report a novel approach for preparing precipitated calcium carbonate for the first time by Bacillus licheniformis using different types of media containing urea as a source of urease enzyme and for the first time using particles of pure calcium. The bacteria used in this study produced urease which catalyzes the hydrolysis of urea (CO(NH2)2) into ammonium (NH4) and carbonate (CO32−) leading to the precipitation of calcium carbonate. Calcium carbonate precipitation was experimentally studied by spontaneous precipitation at various pH (8–12), temperatures (30, 35, 40, 45, 50 °C), and at different concentrations of urease enzyme (1, 5, 10 mg mL−1). The XRD results showed a mixture of calcite and vaterite. The morphology of calcium carbonate particles prepared was studied under SEM after using it as a bioconsolidation of degraded fresco wall paintings.