Characterization of Bacillus atrophaeus Strain from the Composite Material Surface in Arctic Conditions and Its Sensitivity to CuO Nanoparticles.

Metal nanoparticles, particularly copper oxide nanoparticles (CuO-NPs), are regarded as promising biocidal additives for polymer composite materials due to their antimicrobial properties. The bacterial strain Bacillus atrophaeus B.a.-PKm-14 (= VKM-B-4004), isolated from the composite material surface exposed to climatic testing at an open-air testing site in the Sakha Republic (Arctic zone of Russia), was analyzed. It was characterized in terms of its phylogenetic affiliation, physiological characteristics, and sensitivity to 80 ± 10 nm CuO-NPs on solid growth medium. The ability of the strain to grow on various organic substrates was established, the presence of protease and lipolytic activities was confirmed, and the strain resistance to various antimicrobial agents was assessed. The studied microorganism was found to exhibit varying sensitivity to CuO-NPs at temperatures of 15 and 28 °C. At lower temperatures, NPs stimulated its growth at concentrations of 0.05 and 0.1% w/v compared to the control (p < 0.05), which may be attributed to their cryoprotective effect. At 15 °C, a significant bacteriostatic effect of CuO-NPs was observed at concentration of at least 0.2% on solid medium. The minimum bactericidal concentration of CuO-NPs at 28 °C attained 0.25%, which corresponds to the potential capacity of polymer composite materials in terms of their structural properties. The data on the bacteriostatic concentrations of CuO-NPs will contribute to the development of basalt plastic materials with biocidal properties.