Physiochemical analyses and molecular characterization of heavy metal-resistant bacteria from Ilesha gold mining sites in Nigeria

• Published in: Journal of Genetic Engineering and Biotechnology 2023-12, Vol.21 (1), p.172, Article 172
• Main Authors: Ojo, Glory Jesutomisin, Onile, Olugbenga Samson, Momoh, Abdul Onoruoiza, Oyeyemi, Bolaji Fatai, Omoboyede, Victor, Fadahunsi, Adeyinka Ignatius, Onile, Tolulope
• Format: Article
• Language: English
• Subjects: Anniversaries; Bacteria; Bioremediation; Cadmium; Cobalt; Drug resistance in microorganisms; Ecosystems; Enterobacter cloacae; Gold; Gold industry; Gold mines & mining; Heavy metal content; Heavy metals; Lead; Local government; Mercury (metal); Microorganisms; Mineral industry; Mines and mineral resources; Minimum inhibitory concentration; Mining; Mining industry; Physiochemistry; Physiological effects; Physiology; Potassium; Soil water; Water sampling; Zinc
• ISSN: 1687-157X; 2090-5920
• DOI: 10.1186/s43141-023-00607-5

Background The contribution of the processes involved and waste generated during gold mining to the increment of heavy metals concentration in the environment has been well established. While certain heavy metals are required for the normal functioning of an organism, certain heavy metals have been identified for their deleterious effects on the ecosystem and non-physiological roles in organisms. Hence, efforts aimed at reducing their concentration level are crucial. To this end, soil and water samples were collected from Ilesha gold mining, Osun State, Nigeria, and they were subjected to various analyses aimed at evaluating their various physicochemical parameters, heavy metal concentration, heavy metal-resistant bacteria isolation, and other analyses which culminated in the molecular characterization of heavy metal-resistant bacteria. Results Notably, the results obtained from this study revealed that the concentration of heavy metal in the water samples around the mining site was in the order Co > Zn > Cd > Pb > Hg while that of the soil samples was in the order Co > Cd > Pb > Hg > Zn. A minimum inhibitory concentration test performed on the bacteria isolates from the samples revealed some of the isolates could resist as high as 800 ppm of Co, Cd, and Zn, 400 ppm, and 100 ppm of Pb and Hg respectively. Molecular characterization of the isolates revealed them as Priestia aryabhattai and Enterobacter cloacae. Conclusion Further analysis revealed the presence of heavy metal-resistant genes (HMRGs) including merA, cnrA, and pocC in the isolated Enterobacter cloacae. Ultimately, the bacteria identified in this study are good candidates for bioremediation and merit further investigation in efforts to bioremediate heavy metals in gold mining sites.