Insights into Microbial Remediation of Heavy Metals in Soils and Water

Microbial remediation has garnered recognition as an environmentally friendly and cost-effective solution, with applications extending to heavy metal-contaminated soil and water remediation either independently or in conjunction with other methods. The challenge of contamination with heavy metals (HMs) presents a considerable problem, leading to adverse impacts on human welfare, public health, and agricultural productivity. The associated risks from toxic heavy metals due to their persistent and bio-accumulative nature, drive the exploration of microbial processes, including both microbially induced and microbially influenced carbonate precipitation (MICP). Under MICP conditions, ureolytic bacterial strains are capable of immobilization heavy metals(Cr, Zn, Ni, Cu and Cd) along with the precipitation of varying proportions of calcium carbonates and calcium phosphates. Notably, Pseudomonas aeruginosa strains displayed the highest efficiency in Cr removal (100%), while Providencia rettgeri strain achieved complete removal (100%) of Zn. The outcomes of this study revealed that that ureolytic bacteria not only have a tolerance for heavy metal toxicity, reaching concentrations of up to 5 mM, but also co-precipitate heavy metals. This presents a novel biological approach for the simultaneous bioremediation and immobilization of multiple heavy metals through mineral formation. This approach holds significant ecological importance for soil stabilization and alleviation of heavy metal toxicity.