Background: The present study reveals the synthesis of copper oxide nanoparticles (CuO
NPs) by probiotic bacteria (Lactobacillus casei subsp. casei) and demonstrates the cytotoxic effects
of these nanoparticles against gram negative and positive bacteria and cancer cell lines.
Methods: The CuO NPs are biosynthesized from Lactobacillus casei subsp. casei (L. casei) in an
eco-friendly and cost-effective process. These nanoparticles are characterized using Fourier transform
infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), field emission scanning electron
microscopy (FESEM), energy dispersive X-ray (EDX) and transmittance electron microscope (TEM)
analysis. The antibacterial activity is examined by Well-diffusion, minimum inhibitory concentrations
(MIC) and minimum bactericidal concentrations (MBC) assays using Broth microdilution.
Anticancer effects of these nanoparticles are evaluated by methyl thiazolyl diphenyl-tetrazolium
bromide (MTT) assay and Griess test.
Results: Our results confirm the biosynthesis of CuO NPs from L. casei. Antibacterial assays demonstrate
that treatment of gram-negative and gram-positive bacteria with CuO NPs inhibits the
growth of these bacteria. Furthermore, the cell viability of human cancer cells decreases while
treated by nanoparticles. These nanoparticles increase nitric oxide (NO) secretion determined by NO
Conclusion: These results suggest that CuO NPs may exert antibacterial effects as well as cytotoxic
effects on cancer cells by suppressing their growth, increasing the oxidative stress and inducing