Background and Objective: Bacterial biofilm play one important in the pathogenesis and virulence of diseases. Therefore, biofilm control of bacteria is one of the essential and vital goals of medicine. Material and Methods: One cold tolerant bacterium, namely Microbacterium sp. was isolated and identified from high altitude. This bacterium can biosynthesize CuO and ZnONPs extracellularly at 20 °C. Biofilm inhibition was determined by the crystal violet assay. 1.5×106 CFU/mL of S.epidermidis overnight culture was exposed to CuO and ZnONPs solution with different concentrations on 96 microplate wells. To monitor the adherence of bacterial cells, the crystal violet was added. An ELISA microtiter plate reader at 590 nm determined adherent biofilm and percentage of biofilm inhibition was calculated. The biofilm inhibitory effect of the two NPs was confirmed at different concentrations. An increase in the percentage of biofilm inhibition was observed with the increase in the concentration of CuO and ZnONPs as compared to the negative control. Results: For S.epidermidis, the biofilm formation was found to be inhibited by up to 100% at ZnONPs of 250 µg/mL. While, CuONPs at 250 µg/mL concentration able to inhibit only %12 of bacterial biofilm. However, even at a concentration of 16 µg/mL, there was 10% anti-biofilm activity. Conclusion: The results suggest that the CuONPs synthesized from cold tolerant Microbacterium sp. exhibit specific biofilm inhibition and could reduce severity of disease due to S.epidermidis infections.

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