Leveraging a tailor-made approach to enhance the kinetics of a native ureolytic bacterium, Sporosarcina pasteurii...

To bolster the large-scale research in the emerging field of bio-cementation using MICP, it is crucial to refine the nutrient medium that enhances both growth and enzyme kinetics of ureolytic bacteria. The present study systematically optimised the nutrient medium for the isolated native ureolytic bacterium Sporosarcina pasteurii PS3A using statistical approaches and further evaluated its bio-cementation potential. The results showed that cultivating S. pasteurii PS3A in the Opt_PS3A medium significantly enhanced the urease activity (∼10.5-fold) compared to the conventional yeast-ammonium sulphate medium. Moreover, comparing S. pasteurii PS3A with the widely studied S. pasteurii ATCC 11859 under optimised growth conditions has unveiled the exemplary kinetics of the former, bringing it to the scientific limelight. The morphological and mineralogical characteristics of the precipitated compound clearly confirmed the precipitation potential of S. pasteurii PS3A. The multiphase injection of fermentation broth and cementitious solution at optimal dosage into the soil matrix with varying injection rates resulted in a higher unconfined compressive strength of 0.78 ± 0.032 MPa with precipitate distributed uniformly within the soil matrix. These findings signify that the media composition can significantly improve microbial efficiency, providing valuable guidelines for scaling up MICP.