Microbially Induced Sand Cementation Using Lysinibacillus Fusiformis NM01.

Area of Science:

• Geotechnical Engineering
• Microbiology
• Environmental Science

Background:

• Sandy soil stabilization is crucial for infrastructure development.
• Microbially Induced Calcium Carbonate Precipitation (MICP) offers a sustainable alternative to conventional methods.
• Urease-producing bacteria with environmental adaptability are essential for effective MICP.

Purpose of the Study:

• To isolate and characterize a novel urease-producing bacterium from a local carbonate mining area.
• To evaluate the efficacy of the isolated bacterium in sandy soil stabilization using MICP.
• To confirm the mineralogical composition of precipitated calcium carbonate.

Main Methods:

• Isolation and identification of urease-producing bacteria.
• Urease activity assays across various temperatures and pH levels.
• Sand column cementation tests.
• Characterization of precipitated calcium carbonate using SEM, FTIR, and XRD.

Main Results:

• A urease-producing strain, NM01 (Lysinibacillus fusiformis), was isolated with high urease activity (~30 mM/min) and broad environmental adaptability (pH 6-10, 25-35°C).
• Sand column tests showed significant improvement in soil cohesion, increasing unconfined compressive strength (UCS) from 0 to 630 ± 50 kPa.
• Calcium carbonate content increased from 3.81% to 8.99%, with calcite and vaterite identified as the primary mineral phases.

Conclusions:

• Lysinibacillus fusiformis NM01 is an effective ureolytic bacterium for sandy soil stabilization via MICP.
• The isolated strain's robustness and high performance make it a valuable resource for advancing MICP technology.
• This study validates the potential of locally adapted microorganisms for sustainable geotechnical engineering solutions.