Synthesis of bioactive silver nanoparticles by a pseudomonas strain associated with the antarctic psychrophilic protozoon euplotes focardii

• Published in: Marine Drugs
• Main Authors: John M. S., Nagoth J. A., Ramasamy K. P., Mancini A., Giuli G., Natalello A., Ballarini P., Miceli C., Pucciarelli S.
• Other Authors: John, M, Nagoth, J, Ramasamy, K, Mancini, A, Giuli, G, Natalello, A, Ballarini, P, Miceli, C, Pucciarelli, S
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2020
• Subjects: Antibiotic; Green synthesis biomaterial; Nanotechnology; Silver nitrate; FIS/07 - FISICA APPLICATA (A BENI CULTURALI; AMBIENTALI; BIOLOGIA E MEDICINA); Antarc*; Antarctic
• Online Access: http://hdl.handle.net/10281/294868; https://doi.org/10.3390/md18010038

The synthesis of silver nanoparticles (AgNPs) by microorganisms recently gained a greater interest due to its potential to produce them in various sizes and morphologies. In this study, for AgNP biosynthesis, we used a new Pseudomonas strain isolated from a consortium associated with the Antarctic marine ciliate Euplotes focardii. After incubation of Pseudomonas cultures with 1 mM of AgNO3 at 22 °C, we obtained AgNPs within 24 h. Scanning electron (SEM) and transmission electron microscopy (TEM) revealed spherical polydispersed AgNPs in the size range of 20-70 nm. The average size was approximately 50 nm. Energy dispersive X-ray spectroscopy (EDS) showed the presence of a high intensity absorption peak at 3 keV, a distinctive property of nanocrystalline silver products. Fourier transform infrared (FTIR) spectroscopy found the presence of a high amount of AgNP-stabilizing proteins and other secondary metabolites. X-ray diffraction (XRD) revealed a face-centred cubic (fcc) diffraction spectrum with a crystalline nature. A comparative study between the chemically synthesized and Pseudomonas AgNPs revealed a higher antibacterial activity of the latter against common nosocomial pathogen microorganisms, including Escherichia coli, Staphylococcus aureus and Candida albicans. This study reports an efficient, rapid synthesis of stable AgNPs by a new Pseudomonas strain with high antimicrobial activity.