Endophytic Bacteria-Mediated Nanoparticle Synthesis: A Sustainable Approach for Environmental Bioremediation

Environmental contamination by uranium and other heavy metals poses a serious threat to ecosystem stability and human health, necessitating the development of efficient, cost-effective, and environmentally sustainable remediation strategies. Conventional remediation techniques are often associated with high operational costs, energy consumption, and secondary waste generation, highlighting the need for innovative alternatives. In this context, nanobioremediation, which integrates nanotechnology with biological remediation processes, has emerged as a promising approach for the removal, immobilization, and detoxification of environmental pollutants. Among various nanomaterials, biogenic nanoparticles, particularly manganese dioxide nanoparticles, have attracted considerable attention owing to their high surface area, adsorption capacity, and redox activity. The biological synthesis of nanoparticles using microorganisms offers an eco-friendly alternative to conventional physical and chemical methods by reducing the reliance on toxic chemicals and harsh reaction conditions. Endophytic bacteria are particularly valuable in this regard because of their ability to synthesize nanoparticles through intracellular and extracellular mechanisms mediated by bacterial enzymes, proteins, and secondary metabolites. In addition to nanoparticle synthesis, these bacteria contribute to phytoremediation by promoting plant growth, enhancing metal tolerance, producing siderophores and metal-binding compounds, and facilitating the biosorption, chelation, and transformation of heavy metals. Their interactions with nanoparticles may further improve contaminant immobilization, reduce metal bioavailability, and enhance the remediation potential of contaminated soils and wastewater. Previous studies have demonstrated the ability of endophytic bacteria, including Bacillus and Pseudomonas species, to synthesize nanoparticles with antimicrobial and other functional properties, highlighting their broader biotechnological potential. Despite these advances, further research is required to elucidate the mechanisms governing nanoparticle biosynthesis, metal–microbe interactions, long-term environmental stability, and potential ecotoxicological effects. Overall, endophytic bacteria-mediated nanoparticle synthesis represents a promising component of sustainable nanobioremediation, with potential applications in the management of uranium and heavy-metal contamination and the development of environmentally compatible remediation technologies.