Bioleaching of different types of metals by <i>Exiguobacterium himgiriensis</i> isolated from printed circuit board

The ubiquity of electronic devices has made them indispensable in daily life. Nevertheless, this high priority leads to a surge in electronic waste, or e-waste, which is extremely dangerous for the environment and human health. E-waste contributes to environmental pollution and threatens ecosystems and human health. Management of recycling methods and efficient e-waste is crucial to lower these dangers. Traditional recycling techniques are effective, but often release harmful pollutants. The present study has attempted to use the metal-resistant <i>Exiguobacterium himgiriensis</i> isolated from e-waste, such as the Printed Circuit Board (PCB), to investigate its efficiency in removing heavy metals from these substrates. By using ICP-OES, it has been found that this species of bacterium recovered different types of metals (Co 84.67%, Ni 83.25%, Pb 80.17%, Cu 80.06%, Zn 76.71%, Al 76.13%, Fe 71.74%, and Ag 64.97% respectively) within 5 days under laboratory conditions. Detecting structural and functional group changes in the control PCB and bioleached residue by the FT-IR, FE-SEM, EDS, and XRD techniques confirms the evidence of bioleaching. Bacteria can increase their dissolving capacity and decrease surface tension by chemically changing metals. <i>E. himgiriensis</i> bioleaches PCB samples for 5 days, resulting in rougher, uneven surfaces with fractures and fissures. FT-IR spectroscopy reveals the bacterium's impact on metals, particularly Si, O, and Fe. This study could help reduce environmental pollution and health risks associated with e-waste by developing an economical and environmentally friendly method for bioleaching different metals in PCB.