Optimization, Characterization and Antibacterial Activity of Copper Nanoparticles Biosynthesized Using Pantoea...

'Green' synthesis of nanoparticles from microorganisms and plants is a sustainable alternative to the conventional chemo-physical methods because of its environment-friendliness. Microorganisms take up extracellular and intracellular pathways to manufacture nanoparticles. This study was aimed at optimization of the parameters influencing the biosynthesis of Cu/CuONPs (Copper/Copper oxide nanoparticles) by Pantoea agglomerans CPHN2 using OFAT (One-factor-at-a-time) approach. The optimum biotransformation was achieved at 5 mM concentration of CuSO₄, 32 h incubation time, 6 h reaction time, equal mixing ratio of supernatant and CuSO₄, 7 pH, and 23 °C temperature. Biosynthesized Cu/CuONPs along with those formed chemically, were characterized using UV-Visible spectrophotometer, resulting in a characteristic peak between 550 and 650 nm. Dynamic light scattering (DLS) reported that Z-average and Zeta potential of Cu/CuONPs were 291.9 nm and - 21 mV for biosynthesized and 179 nm and - 6.49 mV for chemosynthesized NPs. HR-TEM (High Resolution-Transmission Electron Microscopy) revealed hexagonal NPs in size range of 5-35 nm. In addition, FTIR (Fourier Transform Infrared) spectrum elucidated different peaks attributed to the Cu/CuONPs, alkynes, O-H, and N-H bonds, of the molecules involved in synthesis and stabilization of biosynthesized NPs. Antimicrobial assay conducted in the presence of 100 µg/ml solution of biosynthesized Cu/CuONPs led to 66.01, 68.31, and 55.73%, inhibition of Staphylococcus aureus growth at 7, 14, and 21 h, respectively, whereas chemosynthesized Cu/CuONPs had negligible impact. The biosynthesized NPs also exhibited 5.48-fold increase in inhibitory activity than chemosynthesized NPs on Bacillus subtilis growth. The results suggests that biosynthesized Cu/CuONPs can serve as ecofriendly and economical method for managing the infections led by gram-positive bacteria.

The online version contains supplementary material available at 10.1007/s12088-025-01455-2.