Genetically Engineered Pseudomonas aeruginosa Enhances Siderophore-Mediated Iron Recovery from Coal Fly Ash

Microbial siderophores, potent iron-chelating molecules, offer significant promise for the bioremediation of heavy metal-contaminated industrial wastes. However, their large-scale application remains limited by biological and environmental constraints. In this study, a genetically engineered strain of Pseudomonas aeruginosa, designated BR01, developed by introducing the plasmid pRK-bfmR is presented. Integrated proteomic and transcriptional assays reveal that overexpression of the osmolality-responsive regulator BfmR reprograms cellular metabolism, enhancing iron acquisition pathways while downregulating virulence-associated and non-essential metabolic processes. As a result, strain BR01 demonstrates a 3.82-fold increase in siderophore production (P < 0.01) and a 2.95-fold enhancement in iron extraction from coal fly ash (P < 0.01) compared to the wild type. Further optimization of growth conditions boosts siderophore yield by an additional 1.73–2.48 times (P < 0.01). Moreover, the engineered strain shows improved tolerance to cadmium (Cd) and lead (Pb), indicating its robustness in harsh industrial environments. These findings underscore the potential of genetically optimized bacteria to enhance the sustainability of bioremediation technologies.