Microbial synthesized cadmium oxide nanoparticles induce oxidative stress and protein leakage in bacterial cells

The bactericidal activity of metal oxide nanoparticles (NPs) offers extensive opportunities in bioengineering and biomedicines. Bioengineered transition metals used in various forms against lethal microbes. In this study, Cadmium Oxide nanoparticles (CdO-NPs) were prepared through the co-precipitation method using fungal strain Penicillium oxalicum and cadmium acetate solution. The structure and elemental composition of the prepared NPs were determined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis absorption spectroscopy, scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Antibacterial activity was assessed through well diffusion method against Staphylococcus aureus (S. aureus), Shigella dysenteriae (S. dysenteriae), and Pseudomonas aeruginosa (P. aeruginosa). In addition, reactive oxygen species (ROS), reducing sugars and protein leakage contribution was examined against selected strains. The XRD analysis proved that the synthesized CdO-NPs possess a crystalline structure with an average crystalline size of 40-80 nm. FTIR confirmed the presence of organic compounds on the particle surface, while UV showed stability of the particles. SEM and EDS confirmed that CdO-NPs were successfully prepared and spherical. The maximum zone of inhibition against S. dysenteriae and P. aeruginosa was found and showed a less optical density of 0.086 after 18 h. ROS, reducing sugar, and protein leakage assay showed a significant difference as compared to control. Based on the present study, it is recommended that microbial mediated synthesized nanoparticles can be used as biomedicines for the treatment of different types of bacterial infections.