Experimental Study on the Preparation of a Highly Active Bacterial Suspension for MICP in the South China Sea

Most previous studies investigating the use of microbial-induced calcium carbonate precipitation (MICP) to reinforce foundations have indicated that the final curing effect can be improved by changing the nutrient environment parameters during the MICP reaction. However, using such methods to improve the construction process increases the construction cost and the impact on the surrounding environment. This study was conducted to determine if we could prepare a bacterial suspension with high activity in a short period of time by examining the effects of inoculation time, the concentration of the inoculated bacterial suspension, and shaker speed during expansion to determine whether sporosarcina pasteurii would vigorously grow. Based on the analysis of the pattern of activity variations in the bacterial suspension, the most appropriate growth scheme for preparing high-activity bacterial suspensions when using MICP to strengthen structures in the South China Sea was proposed. In terms of the results, it was found that the trend of changes in activity and the peak time of maximum activity in the bacteriophage cultured under low-speed conditions in the expanded culture tended to be the same. The value of the bacteriophage’s activity was low. During medium speed culture of the bacterial suspension, urease activity peaked much higher than that of the other comparison groups, with the medium speed bacterial broth having the highest peak. As a result of the prolonged shaking incubation time, the effect of prolonged shaking on urease activity in the bacterial suspension was mainly reflected in the fact that the activity decay cycle of the colony itself was slowed.