Biocement can be achieved through the microbially induced carbonate precipitation (MICP) process. Such a method can potentially be utilized as an eco-friendly method for civil and environmental engineering applications such as soil ground improvement and wind erosion control of surface soil. In this method, one key step is the effective production of ureolytic bacteria. In previous laboratory and field studies, the cultivation and production of the bacteria used for the MICP were usually expensive and time-consuming. The purpose of this study was to optimize the cultivation method of the ureolytic bacteria (Sporosarcina pasteurii), and soil stabilization tests were conducted to verify the effectiveness of the cultured bacteria used to strengthen soil against the wind-induced erosion. Bacterial cultivation methods were studied by investigating the effects of different cultivation media and conditions. Testing variables included the types and concentrations of nitrogen sources (urea or NH₄Cl), pH values (7.5–9.5), cultivation conditions (batch or chemostat condition), and different carbon sources. It was found that, with the same amount of nitrogen source, the test with pure urea had the highest biomass yield, urease activity, and specific urease activity than the other tests with pure NH₄Cl or both NH₄Cl and urea. The use of urea as the nitrogen source in the media also led to an increase in pH, which was not found in the test with pure NH₄Cl. As for the factor of urea concentration, the tests with a higher urea concentration had a higher biomass yield, urease activity, and pH. The factor of pH values also played an important role. The test with an 8.5 initial pH value had a higher biomass yield, urease activity, and specific urease activity than the tests with 7.5 and 9.5 initial pH values. In the chemostat condition, the ureolytic bacteria could be effectively produced with urease activity up to 7 mmol/L/min, as compared with around 12 mmol/L/min activity in the batch condition. Thus, the optimum nitrogen source, pH value, and cultivation condition for the cultivation of Sporosarcina pasteurii was urea, 8.5, and batch condition, respectively. In addition, when soybean milk powder or milk powder was used as the carbon source, the urease activity was around 2.5 mmol/L/min, which is also high enough to be used for biocement.

Enzyme-induced carbonate precipitation has been studied for wind erosion control in arid areas. A comparative study was conducted between the pure urease- and crude soybean urease-induced carbonate precipitation methods with the same enzyme activity for enhancing the wind erosion resistance of desert sand. Tube tests were carried out to monitor the amount of organic matter and CaCO₃ precipitates at different reaction times. Two groups of sand specimens received several cycles of treatment with soybean urease (SU) and pure urease (PU), respectively, with urea or without urea. The treated specimens were exposed to wind-blown sand flow to evaluate erosion resistance. The results showed that SU induced more organic precipitation under the salting-out effect, which was 9.88 times higher than that from PU. Under the one-cycle treatment, SU-treated specimens with higher contents of CaCO₃ and organic matter exhibited lower erosion mass. Under the multiple-cycle treatment, the high viscosity of SU and rapid precipitation of organic matter resulted in the inhomogeneous distribution of CaCO₃ (more precipitation at the top). Once the top of SU-treated specimens was eroded, the sand below the top layer was lost rapidly, causing the erosion mass of PU-treated specimens to be 95% lower than that of SU-treated specimens.