Investigation of nanoparticle production ability of thermotolerant bacteria

Nanoparticles can be synthesized physically, chemically and biologically by various methods. Due to the disadvantages of physical and chemical methods used in nanoparticle production, the interest in environmentally friendly, economical and non-toxic biological methods (green synthesis) is increasing day by day. In green synthesis, nanoparticles can be synthesized by using plants, many types of microorganisms and enzymes. In this study, the silver nanoparticle production ability of two different species of thermotolerant bacteria, Anoxybacillus mongoliensis and Bacillus cereus, was investigated. According to this; the supernatants obtained from the liquid cultures of the bacteria tested in the studies were used in the production of silver nanoparticles. The first step in detecting the presence of silver nanoparticles is to determine the characteristic color change and spectroscopic absorption peaks that occur in solutions depending on the surface plasmon resonances of the produced nanoparticles. After this process, various optimization studies (incubation time, temperature and pH) were carried out, the characteristic properties of silver nanoparticles with subsequent analyzes (X-ray Diffraction, Scanning Electron Microscopy and Energy Dispersive X-ray, Fourier Transform Infrared Spectroscopy and High Resolution Transmission Electron Microscopy) were determined. After the analyzes carried out, antimicrobial activities of silver nanoparticles were also investigated. In this process, gram negative Escherichia coli ATCC 25922 and gram positive Staphylococcus aureus ATCC 29213 bacterial species and also Candida albicans ATCC 90028 yeast species were used and the minimum inhibitory concentration (MIC) values of the produced silver nanoparticles on the tested microorganisms were also determined. Key words: Antimicrobial activity, Anoxybacillus mongoliensis, Bacillus cereus, Silver nanoparticle, Thermotolerant bacterium, Green synthesis