Strategies to Enhance the Microbial Urease Production for Efficient Biocementation and Its Challenges and Future Directions: A Review

Microbially Induced Calcite Precipitation (MICP) is an eco-friendly technique that uses microorganisms capable of producing urease to promote calcium carbonate precipitation. Microbial enzymes, especially urease, play an important role in biocementation processes. Earlier studies have investigated urease-producing bacteria, such as Sporosarcina pasteurii, for urease production and biocementation applications. Urease is preferably produced through fermentation processes. Scaling up fermentation systems requires maintaining critical parameters like aeration, mixing efficiency, and pH control at larger volumes. To improve microbial urease production, various factors have been optimized, including pH, temperature, nutrient composition of the production medium, alternative nutrient sources such as corn steep liquor and amino acid supplements, nickel availability, and urea concentration. This review provides an overview of microbial sources and fermentation strategies aimed at increasing urease production through optimization of culture conditions, medium composition, and process parameters. The review also highlights low-cost strategies, including the use of agro-industrial waste substrates, immobilized cell systems, and continuous bioreactors. Furthermore, it discusses the application of microbial urease in biocementation, including improvements in biocementation performance, and long-term durability. Despite these advances, challenges remain, particularly enzyme instability, variable field conditions, and scale-up difficulties.