Microbially Induced Sand Cementation Using Lysinibacillus fusiformis NM01

Microbial-induced calcium carbonate precipitation (MICP) is a novel sand solidification technique that has garnered significant attention in recent years. A key challenge for the application of MICP technology is the environmental adaptability of urease-producing strains. This study successfully screened a urease-producing bacterial strain, NM01, from a local calcium carbonate mining area. NM01, identified as Lysinibacillus fusiformis via 16S rDNA analysis, demonstrated effective biomineralization. The growth characteristics of NM01 and its urease activity were investigated under varying temperature and pH conditions. Sand column solidification tests were conducted to evaluate their mentation effect, and the resulting biomineralization products were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results indicate that NM01 exhibits robust growth and high urease activity (approximately 30 mM/min) within a temperature range of 25 to 35 °C and a pH range of 6 to 10. In the sand column cementation tests, NM01 effectively solidified loose sand into cohesive structures with measurable mechanical strength, increasing the unconfined compressive strength (UCS) from 0 to 0.63 ±0.03 MPa. The effect of inducing calcium carbonate precipitation was significant, and the content of calcium carbonate in the gravel increased from 3.81% to 8.99%. XRD and FTIR analyses confirmed the successful precipitation of calcium carbonate and biomineralization-mediated sand solidification by NM01. SEM observations, combined with XRD results, revealed that the calcium carbonate precipitates induced by NM01 primarily existed in the forms of calcite and vaterite. The successful isolation of this locally adapted urease-producing bacterium provides a valuable option for the broader application of MICP technology.