Perspectives on sustainable bioprocesses for Microbially Induced Calcium Carbonate Precipitation (MICP)

Microbially induced calcium carbonate precipitation (MICP) represents a promising alternative to conventional construction methods, which are frequently associated with environmental concerns. However, the production of adequate microbial biomass in a sustainable manner remains a major obstacle to industrial MICP applications. Thus, this review evaluates strategies to enable sustainable cultivation of MICP-relevant microorganisms by addressing three interdependent components: strain selection, media formulation, and bioprocess operation. First, sustainable strains must combine aspects of nutrient requirements, formation of harmful microbial byproducts, effective precipitation performance in the respective application, and environmental compatibility. Adherence to national regulatory requirements is necessary, as they can limit field application, especially for genetically engineered systems. Secondly, the cost of media formulation can be reduced by 90-95% through the substitution of refined substrates with low-grade chemicals. Moreover, waste-derived components, such as industrial side streams, can further enhance sustainability. However, their supplementation with additional nutrients is mostly required. Lastly, at the level of bioprocess, energy-intensive sterilization can be mitigated via selective or non-sterile cultivation. Moreover, the potential for premature precipitation during reactor operation must be considered. Thus, coordinated application-dependent optimization across strains, media, and bioprocesses is essential to achieve sustainable cultivation for MICP, enabling broader industrial adoption.