PubMed2026
Heavy metal pollution from tannery industries presents significant environmental and public health concerns due to the toxicity and persistence of metals such as Pb2+ and Cd2+. This study aimed to isolate and characterize indigenous Pb2+ and Cd2+-tolerant bacteria from tannery effluents and contaminated soils of highly polluted areas in Dhaka for potential bioremediation applications. A total of 72 Pb2+-tolerant and 52 Cd2+-tolerant bacterial isolates were obtained using metal-supplemented LB agar. The minimum inhibitory concentrations (MICs) recorded were 4000 ppm for Pb2+ and 250 ppm for Cd2+. Quantitative analysis demonstrated removal efficiencies of 93.91% for Pb2+ and 89.66% for Cd2+. All isolates exhibited plant growth-promoting traits, including phosphate solubilization, ammonia production, indole-3-acetic acid (IAA) production, and cellulase activity. Most isolates were antibiotic-sensitive, though some showed multidrug resistance, emphasizing the need for biosafety evaluation. The most promising isolates were partially identified as Enterobacter spp. and K. pneumoniae. Protein expression profiling by SDS-PAGE revealed metal-responsive proteins ranging from 25 to 75 kDa under selective Pb2+ and Cd2+ stress. Genomic and proteomic analyses further indicated the involvement of efflux pump-associated genes in metal resistance, where cusR was identified as a common resistance gene among the dominant strains. Overall, these findings suggest that the indigenous K. pneumoniae possesses strong potential for Pb2+ and Cd2+ removal, along with plant growth-promoting capabilities, making them promising candidate for bioremediation and phytoremediation strategies.