The Role of Microorganisms in the Nucleation of Carbonates, Environmental Implications and Applications

Microbially induced carbonate precipitation (MICP) is an important process in the synthesis of carbonate minerals, and thus, it is widely explored as a novel approach with potential for many technological applications. However, the processes and mechanisms involved in carbonate mineral formation in the presence of microbes are not yet fully understood. This review covers the current knowledge regarding the role of microbial cells and metabolic products (e.g., extracellular polymeric substances, proteins and amino acids) on the adsorption of divalent metals, adsorption of ionic species and as templates for crystal nucleation. Moreover, they can play a role in the mineral precipitation, size, morphology and lattice. By understanding how microbes and their metabolic products promote suitable physicochemical conditions (pH, Mg/Ca ratio and free CO₃²⁻ ions) to induce carbonate nucleation and precipitation, the manipulation of the final mineral precipitates could be a reality for (geo)biotechnological approaches. The applications and implications of biogenic carbonates in areas such as geology and engineering are presented and discussed in this review, with a major focus on biotechnology.