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Synthesis of Bioactive Silver Nanoparticles by a Pseudomonas Strain Associated with the Antarctic Psychrophilic Protozoon Euplotes focardii

1
School of Biosciences and Veterinary Medicine, University of Camerino, 62032 Camerino, Italy
2
School of Sciences and Technology, University of Camerino, 62032 Camerino, Italy
3
Department of Biotechnology and Biosciences, University of Milano-Bicocca, 20126 Milano, Italy
*
Author to whom correspondence should be addressed.
Mar. Drugs 2020, 18(1), 38; https://doi.org/10.3390/md18010038
Received: 30 November 2019 / Revised: 27 December 2019 / Accepted: 31 December 2019 / Published: 3 January 2020
(This article belongs to the Special Issue Bioactive Molecules from Extreme Environments)
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. View Full-Text
Keywords: green synthesis biomaterials; silver nitrate; antibiotics; nanotechnology green synthesis biomaterials; silver nitrate; antibiotics; nanotechnology
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John, M.S.; Nagoth, J.A.; Ramasamy, K.P.; Mancini, A.; Giuli, G.; Natalello, A.; Ballarini, P.; Miceli, C.; Pucciarelli, S. Synthesis of Bioactive Silver Nanoparticles by a Pseudomonas Strain Associated with the Antarctic Psychrophilic Protozoon Euplotes focardii. Mar. Drugs 2020, 18, 38.

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