Bioremediation of Heavy Metal-contaminated Soils Using Microorganisms: A Comprehensive Review

Heavy metal (HM) contamination of soils has become a critical environmental issue due to rapid industrialization, urbanization, and intensified agricultural activities. These metals are persistent, non-biodegradable, and toxic, posing serious risks to plant growth, soil health, and human well-being through the food chain. Elevated concentrations of heavy metals disrupt plant physiological processes, induce oxidative stress, and alter soil microbial community structure, thereby reducing soil fertility and agricultural productivity. Conventional remediation techniques, including physical and chemical methods, are often costly, time-consuming, and environmentally unsustainable. Microbial bioremediation has emerged as an eco-friendly, cost-effective, and sustainable alternative for the detoxification of heavy metal-contaminated soils. This review provides a comprehensive overview of the sources and impacts of heavy metals and critically examines microbial mechanisms such as biosorption, bioaccumulation, biotransformation, and detoxification. The role of plant-microbe interactions, particularly in the rhizosphere, is also highlighted in enhancing remediation efficiency. Furthermore, recent advances, including the application of microbial consortia and genetically engineered microorganisms, are discussed along with their associated challenges. The review also identifies key research gaps and future directions, emphasizing the need for field-scale validation and integrated approaches to improve the efficiency and applicability of microbial bioremediation strategies.