Microbially Induced Carbonate Precipitation (MICP) for Cadmium Removal: Sustainable Applications for Ecosystem Protection

Introduction
Heavy-metal pollution represents a critical threat to environmental and public health due to the persistence, non-biodegradability, and bioaccumulative nature of these elements. Contaminated waters used for agriculture, drinking, or discharged as urban wastewater constitute major exposure routes for humans and ecosystems. In recent years, nature-based bioremediation strategies employing non-pathogenic microorganisms have gained attention for the selective removal of dissolved metals. Among these, bacterially induced bioprecipitation has emerged as a promising approach due to its efficiency, specificity, and operational sustainability.

Methods
This study evaluated the capacity of selected non-pathogenic ureolytic bacteria to induce co-precipitation of Cd²⁺ as a carbonate mineral phase. Two microbial strains, Vibrio harveyi and Glutamicibacter bergerei, known for catalyzing ureolysis-driven increases in pH and carbonate alkalinity, were tested. Cultures were grown in defined liquid media supplemented with urea and NaCl under controlled laboratory conditions (30 °C, initial pH 7.0, continuous aeration). Cadmium was introduced at an initial concentration of 50 ppm in synthetic contaminated-water matrices. Incubations were carried out for 8 days, with periodic sampling for quantitative analysis of residual metal concentrations using standard chemical methods. Statistical analyses were applied to assess strain-dependent differences and the significance of operational variables.

Results
Both bacterial strains demonstrated notable Cd²⁺ removal through microbially induced carbonate precipitation, forming predominantly insoluble metal–carbonate compounds. Removal efficiencies approached 80%, highlighting the strong potential of ureolytic bioprecipitation for application in contaminated-water treatment.

Conclusion
The proposed biotechnology offers an environmentally sustainable remediation option, generating no toxic by-products and enabling in-situ deployment without chemical additives. These findings provide a scientific basis for further optimization and pilot-scale implementation. The study presenting a solid nature-based strategy for mitigating heavy-metal contamination in aquatic systems.