Biomineralization Performance of Bacillus sphaericus under the Action of Bacillus mucilaginosus

Abstract

Microbial Induced Calcite Precipitation (MICP) is a biochemical process widely found in nature, also known as microbial mineralization. This paper investigates whether this process can help promote the intelligent reinforcement and repair of underground projects such as mines and tunnels. We selected Bacillus sphaericus and Bacillus mucilaginosus as the research objects. The former has an outstanding urease production ability, and the latter can secrete carbonic anhydrase in vitro. Bacillus mucilaginosus was introduced into the culture solution of Bacillus sphaericus in the most suitable culture environment, and the changes of mineralization rate and mineralization yield of Bacillus sphaericus were observed and analyzed. The results revealed that, to maintain the highest growth rate of Bacillus sphaericus, the optimal pH value was between 7 and 8, the optimal urea concentration was 0.5 mol/L, the optimal Ca ²⁺ concentration was 0.6 mol/L, and the optimal Luria-Bertani (LB) culture concentration was 20 g/L. The amount of biomineralized calcium carbonate precipitated in the double bacteria solution can reach 1.89 times the amount of the precipitation in the Bacillus sphaericus solution under the same conditions. It concludes that the introduction of Bacillus mucilaginosus can effectively increase the mineralization yield of Bacillus sphaericus without affecting the mineralized products.