Effects of silver nanoparticles on Thermophilic Geobacillus vulcani 2CX and its enzymes

In recent years, the rapid increase in the use of nanoparticles both in the industrial sector and in home applications has caused such materials to be released into the nature more. The effects of these materials designed with nanoparticles on environmental processes and the organisms that perform them cannot be measured exactly. Considering this information gap, the effect of silver nanoparticles (AgNP) at various concentrations (62,5-1000 μg mL-1) on the growth of thermophilic Geobacillus vulcani 2Cx bacteria, cell membrane permeability, interaction with nanoparticles, cell morphology, and physiological activities was aimed in this study. When the growth inhibition of bacteria due to increased AgNP concentration for G. vulcani 2Cx was examined and compared to the control, it was determined that the growth of bacteria was 71% in the presence of 62,5 μg mL-1 AgNP while it was 96% in the presence of 1000 μg mL⁻¹AgNP. The cell morphology (TEM experiments) and interaction with NP (FT-IR experiments) show that the cell wall, cell membrane structures and the protein and DNA structure in the cell may be degraded. Cell viability decreased with increasing AgNP concentration and G. vulcani 2Cx showed the highest cell viability with 62% at 62,5 μg mL⁻¹ AgNP concentration. When the spectral measurements of G. vulcani 2Cx related to superoxide production at 570 nm were examined, it was determined that it had an absorbance value of 1,6 in the presence of μg mL⁻¹ AgNP and 2,28 in the presence of 1000 μg mL⁻¹ AgNP. It was determined that nanoparticles caused a significant increase in superoxide production depending on the dose and that the enzyme biosynthesis decreased with increasing AgNP concentration. Thus, the enzyme activity was 41% in the presence of 62,5 μg mL-1 AgNP and 29% in the presence of 500 μg mL-1AgNP. When the effect of AgNP on enzyme secretion was examined, it was determined that the enzyme secretion for G. vulcani 2Cx was 32% in the presence of 250 mg mL-1 AgNP when compared to the control. Therefore, it was concluded that AgNPs could exert strong antibacterial effects when applied to closely related microorganisms.