Genomic Analysis and Biomineralization Efficacy of Bacillus megaterium SS3 for Improving Durability Properties of...

Urease-producing microorganisms play an important role in biomineralization through microbially induced calcium carbonate precipitation (MICCP), contributing to enhanced durability and extended lifespan of construction materials in civil engineering. This study investigates the MICCP capabilities of a ureolytic strain, Bacillus megaterium SS3, isolated from alkaline calcareous soil, which showed native adaptation to high-pH environments typical of cementitious materials. Bacillus megaterium exhibited maximum urease activity (625 U/mL) and promoted CaCO₃ precipitation up to 177.3 mg/100 mL. Its incorporation into cement mortar enhanced compressive strength by 18.9% and 10.58% at 7 and 28 days of curing, respectively, and significantly reduced water absorption compared to control specimens. Whole-genome sequencing and gene annotation revealed three structural urease genes (ureA, ureB, ureC) and four accessory urease genes (ureD, ureE, ureF, ureG), providing molecular insight into its biomineralization potential. To validate structure-function relationships, urease enzyme was modelled and molecular docking was performed with urea. The predicted structure showed strong binding at the catalytic site with key residues and nickel ions, confirming enzymatic suitability for MICCP. Bacillus megaterium SS3 not only exhibits effective MICCP performance but also showed enhanced environmental resilience when incorporated into mortar structures, positioning it as a strong candidate for microbial biocementation in civil engineering applications. This is the first report to integrate genome annotation, protein docking, and real-world application in mortar, positioning B. megaterium SS3 as a novel, genome-validated, biomineralizing strain for sustainable construction.