Biosorption of heavy metal using Aspergillus niger: An eco-friendly approach for lead remediation

Heavy metal contamination has emerged as a major environmental concern due to its persistence, toxicity and bioaccumulation in ecosystems. Among these, lead (Pb) poses serious environmental and public health risks due to industrialisation and urbanisation. These non-biodegradable metals persist in ecosystems, bioaccumulate through food chains causing carcinogenic and teratogenic effects. Conventional heavy metal removal methods are often costly and inefficient at low concentrations, necessitating alternative remediation approaches. This study investigated in vitro training of Aspergillus niger against lead sulphate and evaluated the biosorption capacity of trained fungal biomass for lead removal from aqueous solutions. Fungal strains isolated from Meerut district soils (Uttar Pradesh, India) were progressively trained on lead sulphate-supplemented media (1000–4000 ppm). Biosorption experiments were conducted at Chaudhary Charan Singh (CCS) University, Meerut (January - June 2016), using trained and untrained biomass (10–40 mg) in lead solutions (100 and 200 ppm) with 10 min contact time. The training regimen revealed concentration-dependent growth responses, with maximum radial growth stimulation of 68 % observed at 2500 ppm, while concentrations exceeding 3000 ppm exhibited growth inhibitory effects. At 100 ppm, untrained 10 mg biomass showed highest biosorption (68.39 %) with Q-value of 341.95 mg/g. Trained M1 biomass (1000 ppm) exhibited 61.63 % biosorption with Q-value of 308.15 mg/g. At 200 ppm, trained M1 biomass demonstrated superior performance (44.28 %) compared to control (41.40 %). Freundlich isotherm model (R² = 0.984 for control at 100 ppm) showed better fit than Langmuir model, suggesting multilayer adsorption and heterogeneous surface binding. Overall, in vitro metal training enhanced fungal tolerance while maintaining effective biosorption capacity, highlighting its potential for sustainable lead remediation from contaminated waters.