Background and Objective: Green nanotechnology is a branch of nanotechnology concerning the synthesis of nanoparticles with the least amount of hazardous substances. In this study, synthesize and characterize the CuONPs synthesized from the a cold-tolerant strain of Microbacterium isolated from high altitudes and their antibacterial properties was investigated. Material and Methods: The strain was cultured in TSB medium and incubated at 20 °C for 3 days. 1 mM Cu nitrate solution was added to the cell lysis of medium culture. The chang of the color to green, indicating the formation of CuONPs. The UV-visible and XRD spectroscopy were used to determine the purity and size of the nanoparticle. The antimicrobial property of CuO nanoparticles was evaluated using microdilution method using ELISA. The pathogenic bacteria of Escherichia coli and Staphylococcus aureus were exposed to different concentrations of CuONPs in Muller Hinton broth medium and incubated at of 37 °C for 24 hours. Results: An absorption peak at 300-400 nm indecating presence of CuO nanoparticles. CuO nanoparticles have a minimum inhibitory concentration (MIC) of 125 µg/L and 250 µg/L for E.coli and S.aureus, respectively. Conclusion: The results suggest that the CuONPs synthesized from cold-tolerant strains could be good candidates for use in medical applications.

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