Biosynthesis, characterization and antibacterial activity of copper oxide nanoparticles (CuO NPs) from actinomycetes

The aim of the present study was actinomycetes mediated biosynthesis of copper oxide nanoparticles (CuO NPs) and evaluation of its antibacterial activity against selected human and fish pathogens. The biosynthesized CuO NPs were characterized by UV-Visible (UV-Vis) spectroscopy. The presence of capping agents over the metal nanoparticles was confirmed by Fourier-Transform Infrared Spectroscopy (FT-IR). The crystalline nature of the CuO NPs was illustrated by X-Ray diffractometer (XRD). The average size of the biosynthesized CuO NPs from XRD and Transmission Electron Microscopy (TEM) was 61.7 nm. The XRD and Energy Dispersive X-Ray spectroscopy (EDX) suggests the purity of the biosynthesized CuO NPs. The morphology and size was viewed under Scanning Electron Microscopy (SEM). The Dynamic Light Scattering (DLS) results provided the zeta potential of -31.1 mV which further confirmed the stability of the CuO NPs. The biosynthesized CuO NPs showed higher antibacterial activity (zone of inhibition) against various human and fish bacterial pathogens (Staphylococcus aureus, Bacillus cereus, Proteus mirabilis, Edwardsiella tarda, Aeromonas caviae, Aeromonas hydrophila and Vibrio anguillarum). The antibacterial activity of CuO NPs was significantly higher than the activity exhibited by cell free supernatant of actinomycetes. Among the pathogens tested B. cereus was more susceptible (25.3 mm) to biosynthesized CuO NPs. The antibacterial activity exhibited by the actinomycetes mediated biosynthesized CuO NPs suggests that it can combat both human as well as fish bacterial pathogens. To the best of our knowledge, this is the first report on actinomycetes mediated biosynthesis of CuO NPs.