Evaluation of Heavy Metal Removal Efficiency and Molecular Mechanisms of Metal Resistance in Bacteria Isolated from E-Waste Contaminated Soil
Main Article Content
Abstract
The improper disposal and recycling of electronic waste (e-waste) have led to severe contamination of soils with toxic heavy metals, posing serious environmental and health risks. This study evaluated the heavy metal removal efficiency and underlying molecular mechanisms of metal resistance in bacteria isolated from e-waste contaminated soils. Selected bacterial isolates were assessed for their ability to remove lead, cadmium, chromium, and nickel through batch experiments. Metal removal efficiency was quantified, and the contributions of biosorption, bioaccumulation, and extracellular polymeric substance (EPS) production were examined. Molecular investigations were conducted to detect and analyze key metal resistance genes associated with efflux and detoxification mechanisms. The results demonstrated substantial variation among isolates, with certain strains exhibiting high multi-metal removal efficiency supported by elevated EPS production and the presence of multiple resistance genes. The integration of functional performance and molecular evidence confirms that indigenous bacteria from e-waste affected soils possess strong adaptive and detoxification capabilities. These findings highlight their potential application as sustainable and eco-friendly agents for bioremediation of heavy metal contaminated environments.
Article Details
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
References
J. Wuana and F. Okieimen, “Heavy metals in contaminated soils: A review of sources, chemistry, risks and best available strategies for remediation,” ISRN Ecology, vol. 2011, Art. no. 402647, 2011, doi: 10.5402/2011/402647.
A. M. Ayilara, O. S. Olanrewaju, O. O. Babalola, and O. O. Odeyemi, “Bioremediation of heavy metals: Microbial processes and mechanisms,” Frontiers in Environmental Science, vol. 8, Art. no. 587464, 2020, doi: 10.3389/fenvs.2020.587464.
S. Silver and L. T. Phung, “A bacterial view of the periodic table: Genes and proteins for toxic inorganic ions,” Journal of Industrial Microbiology and Biotechnology, vol. 32, no. 11–12, pp. 587–605, 2005, doi: 10.1007/s10295-005-0019-6.
P. Kaur and R. K. Manhas, “Bacterial communities in heavy metal contaminated soils: Diversity, resistance mechanisms and bioremediation potential,” Chemosphere, vol. 286, Art. no. 131646, 2022, doi: 10.1016/j.chemosphere.2021.131646.
S. Abbas, M. Rafatullah, N. Ismail, and A. Lalung, “Isolation, identification, and characterization of heavy metal resistant bacteria from contaminated soil,” Frontiers in Microbiology, vol. 12, Art. no. 742062, 2021, doi: 10.3389/fmicb.2021.742062.
P. K. Singh, R. K. Tiwari, and A. Sharma, “Molecular characterization and metal removal potential of heavy metal tolerant bacteria isolated from industrially contaminated soils,” Environmental Technology & Innovation, vol. 23, Art. no. 101640, 2021, doi: 10.1016/j.eti.2021.101640.
L. Zhang et al., “Phylogenetic diversity and metal resistance genes in bacteria isolated from electronic waste recycling sites,” Science of the Total Environment, vol. 807, Art. no. 150873, 2022, doi: 10.1016/j.scitotenv.2021.150873.
P. Wang et al., “Molecular characterization of heavy metal resistant bacteria from contaminated soils and their bioremediation potential,” Environmental Research, vol. 214, Art. no. 113884, 2022, doi: 10.1016/j.envres.2022.113884.
S. K. Das and A. Dash, “Microbial strategies for heavy metal bioremediation: Recent advances and future prospects,” Bioresource Technology Reports, vol. 19, Art. no. 101121, 2022, doi: 10.1016/j.biteb.2022.101121.
M. H. Shahid et al., “Metal resistance mechanisms and bioremediation potential of bacteria isolated from polluted environments,” Environmental Science and Pollution Research, vol. 29, no. 12, pp. 17845–17860, 2022, doi: 10.1007/s11356-021-16891-4.
R. Kumar, A. Singh, and N. Kaur, “Evaluation of biosorption and bioaccumulation mechanisms in heavy metal resistant bacteria,” Journal of Environmental Management, vol. 320, Art. no. 115792, 2022, doi: 10.1016/j.jenvman.2022.115792.
J. Liu, Y. Li, and Z. Chen, “Functional and molecular assessment of metal-resistant bacteria isolated from contaminated soils,” Journal of Basic Microbiology, vol. 63, no. 4, pp. 331–342, 2023, doi: 10.1002/jobm.202200436.
N. Sharma, P. K. Verma, and S. Gupta, “Heavy metal removal efficiency and resistance genes in indigenous soil bacteria,” Environmental Advances, vol. 13, Art. no. 100402, 2023, doi: 10.1016/j.envadv.2023.100402.
Y. Zhou et al., “Genomic and molecular insights into heavy metal resistance and detoxification in soil bacteria from e-waste recycling areas,” Frontiers in Microbiology, vol. 15, Art. no. 1294473, 2024, doi: 10.3389/fmicb.2024.1294473.
S. Wang, Y. Chen, and H. Li, “Role of extracellular polymeric substances in bacterial heavy metal removal: A molecular perspective,” Environmental Pollution, vol. 327, Art. no. 121570, 2023, doi: 10.1016/j.envpol.2023.121570.
M. A. Islam et al., “Heavy metal removal and resistance mechanisms in bacteria: Implications for sustainable bioremediation,” Journal of Hazardous Materials, vol. 455, Art. no. 131512, 2024, doi: 10.1016/j.jhazmat.2023.131512.