In press. Induced Biomineralization of Calcium Carbonate Using Mesophilic Bacteria in Noncommercial Culture Media

Biomineralization is a natural process whichere living organisms induce mineral formation. In this study, we investigated the induced biomineralization of calcium carbonate (CaCO₃) by a specific strain of gram-positive bacilli previously isolated from mines in Antioquia. This strain was used to assess its ability to precipitate calcium carbonate in an alternative culture medium based on agroindustrial carrot residues, named Foxy Carrot (FC), and its effectiveness was compared with that of the conventional medium B4. A variant of the Foxy Carrot medium, called Foxy Carrot Modified (FC Modified), was also investigated. A Gram-positive bacilli strain, specifically from the genus Bacillus, was identified as the main agent of biomineralization through biochemical tests and molecular techniques. Qualitative and quantitative analyses confirmed the significant potential of this method for calcium carbonate precipitation. The mineral products were characterized using Fourier-transform infrared spectroscopy (FTIR), which revealed spectral features associated with the calcite and aragonite phases of calcium carbonate. The experimental design focused on optimizing the cultivation conditions to maximize microbial activity and mineral precipitation, varying parameters such as pH, temperature, and nutrient availability to assess their impact on biomineralization. Statistical analyses showed that pH had an effect on biomineralization, with a p-value of 0.7037, indicating that while pH influences the process, it is not the most determining factor. In comparison, the conventional medium B4 and Foxy Carrot (FC) medium showed similar calcium carbonate crystal production, with 32 mg per 17 mL for B4 and 30 mg per 17 mL for FC. However, the Foxy Carrot Modified (FC Modified) medium demonstrated superior production of 53 mg in 17 mL. This result suggests that modifications to the Foxy Carrot medium can enhance biomineralization. The analysis revealed significant differences in efficiency between the culture media, with a p-value of 6.586e-09. This indicates that variations in medium formulation have a considerable impact on the ability of microorganisms to induce calcium carbonate precipitation.