Biomineralization of Calcium Carbonate by Bacillus Cereus for Self-healing Biocement

Abstract

Concrete cracks can induce the disruption of dams, bridges, tunnels, and some structures that assist the human life. The agglomeration component of the concrete and the most applied compound, the Portland Cement, can be utilized in combination with calcium lactate and the Bacillus bacteria to produce the crystals of CaCO3 (raw material of the cement production) through adsorption, biomineralization, and crystallization, reducing the risk of ruptures. Thus, a screening of the biotechnological potential of bacterium Bacillus cereus (UCP 1615) under a concentration of 107 cells/mL was carried out to evaluate the production of CaCO3 crystals with 20 g of the Portland Cement II (PC-II), and 0,58, 1,00, and 1,42 g of calcium lactate. These Petri Dishes were incubated at 28°C and during 168 h. Besides, the crystals produced the B. cereus were analysed by an X-Ray Diffractometer (XRD) to estimate the relation (%) between the mainly and possible components. After 17 h, some crystals had already started to appear in the Petri Dishes of 1,00 and 1,42 g of calcium lactate, and after 168 h, the crystals were scraped of all Petri Dishes. The diffractometric analyse of the condition with the highest lactate condition, of 1,42 g, presented percentages of 82% SiO2 (basic structure of cement) and 18% CaCO3. Therefore, the B. cereus strain shows a biotechnological potential to produce crystals of CaCO3 and that this bacterium is able to be tested under different conditions of calcium lactate, microbial concentration, and water according to a factorial design. Keywords: Concrete cracks. Calcium Lactate. Crystals. XRD.