Biosynthesis of copper oxide nanoparticles using extract from Daucus carota L leaves and the antibacterial activity against foodborne bacteria

Research interest continues to grow in the field of green synthesis routes to nanomaterials, specifically on the biologically relevant metal oxide nanoparticles that have antimicrobial potency. This green approach allows the utilization of extracts of different parts of plants such as leaves, barks, fruits and flowers for the synthesis of nanomaterials. In the present study, the leaf extract of Daucus carota L has been used to prepare copper oxide (CuO) nanoparticles (NPs). The synthesized NPs have been characterized by several techniques such as X-ray diffraction analysis, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, transmission and scanning electron microscopy and energy dispersive X-ray analysis. The absorption spectroscopy showed a maximum absorption peak around 300 nm, while the electronic microscopies confirmed a spherical morphology with an average particle size of 47 nm. The CuO NPs were screened against foodborne pathogenic bacteria including Salmonella enterica Typhimurium ATCC 14028, Listeria monocytogenes ATCC 19117, Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538. An agar well diffusion method was utilized for the antimicrobial assay and the minimum inhibitory concentrations were determined. The biosynthesized CuO NPs exhibited more antibacterial potency against the Gram +ve bacteria compared to Gram −ve bacteria. The results obtained were encouraging and recommend CuO NPs as an alternative antimicrobial agent in food preservation.