Leveraging stability dynamics of spore germination for microbially enhanced mineralization of bioconcrete

Microbially induced biomineralization (MIBM) is a trending biotechnological application with the potential to be used in the engineering of built environment; however, it is limited by premature germination of spores due to stresses during concrete mixing. We investigated the germination dynamics of Paenibacillus alkaliterreae (PA) spores under variable temperature, pH, and salinity levels to identify the operating ranges conducive for spore germination and biomineralization in an outdoor environment. To prevent premature germination, the spores were covered with a protective coating of extracellular polymeric substance (EPS). The spores germinated and biomineralized CaCO₃ across environmental conditions of 25-37°C, 0.5-4% NaCl, and pH 6-10. EPS-coated spores achieved 88 ± 2.8% self-healing in 28 days compared with 72 ± 2.7% in free spores. Chemical and morphological characterization confirmed that the bioconcrete comprised CaCO₃ biomineral in the form calcite, which improved the strength, durability, and quality of this bioconcrete over conventional concrete.