Carbonate polymorph formation in microbially induced calcium carbonate precipitation (MICP): Influencing factors, mechanisms, and knowledge gaps

Microbial mineralization of calcium carbonate is a significant geological and environmental process that provides insights into the evolution of life, ancient environments, and biogeochemical cycling of elements. This manuscript thoroughly examines the factors influencing the formation of different calcium carbonate polymorphs induced by bacteria and their implications in various engineering applications. It distinguishes among three types of microbial mineralization: microbially induced, influenced, and controlled, while outlining the metabolic pathways that facilitate calcium carbonate formation. The roles of extracellular polysaccharides (EPS) and S-layer proteins in mineral nucleation are also explored. Cultivation conditions, including media composition and the presence of amino acids, significantly impact polymorph selection, while genomic and transcriptomic studies illuminate bacterial mechanisms underlying calcium carbonate precipitation. The manuscript addresses current knowledge gaps and challenges in understanding how bacteria select calcium carbonate polymorphs, highlighting the need for further research on bacterial strain specificity, culture conditions, and the influence of bacterial cell wall composition on polymorph formation. Overall, this manuscript provides a comprehensive overview of bacterial calcium carbonate mineralization, offering valuable insights for both scientific research and engineering applications.