Application of Response Surface Methodology for Carbonate Precipitation Production Induced by a Mutant Strain of Sporosarcina pasteurii

The application of microbial technology has brought new opportunities for the development of civil engineering. Microbial induced carbonate precipitation (MICP), which use microbial catalyzed hydrolysis of urea to produce calcium carbonate crystals chemically and physically similar to sandstone, could increase strength and stiffness of sands or stones. In this work we investigated the process of calcium carbonate precipitation induced by Sporosarcina pasteurii. To improve the yield of calcium carbonate precipitation, the strain of S. pasteurii was isolated and screened after NTG (N-methyl-N"-nitroso-N-nitrosoguanidine) mutated. Mutant strain B-20 gave the highest MICP production. The urease activity was tested on different medium with byproducts; soyabean meal was the selected major components of medium. Then, the optimization of culture medium for enhanced urease activity was conducted employing response surface methodology. Plackett-Burman design was firstly used to screen the most important variables, and subsequently central composite design was adopted to investigate the optimum value of the selected factors for achieving maximum urease activity and MICP yield.