Content area
Full Text
http://crossmark.crossref.org/dialog/?doi=10.1007/s10534-016-9918-4&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s10534-016-9918-4&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s10534-016-9918-4&domain=pdf
Web End = Biometals (2016) 29:321331 DOI 10.1007/s10534-016-9918-4
http://crossmark.crossref.org/dialog/?doi=10.1007/s10534-016-9918-4&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s10534-016-9918-4&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s10534-016-9918-4&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s10534-016-9918-4&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s10534-016-9918-4&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s10534-016-9918-4&domain=pdf
Web End = http://crossmark.crossref.org/dialog/?doi=10.1007/s10534-016-9918-4&domain=pdf
Web End = Polysaccharide-based silver nanoparticles synthesizedby Klebsiella oxytoca DSM 29614 cause DNA fragmentation in E. coli cells
Franco Baldi . Salvatore Daniele . Michele Gallo . Stefano Paganelli . Dario Battistel . Oreste Piccolo . Claudia Faleri . Anna Maria Puglia . Giuseppe Gallo
Received: 26 November 2015 / Accepted: 15 February 2016 / Published online: 17 February 2016 Springer Science+Business Media New York 2016
Abstract Silver nanoparticles (AgNPs), embedded into a specic exopolysaccharide (EPS), were produced by Klebsiella oxytoca DSM 29614 by adding AgNO3 to the cultures during exponential growth phase. In particular, under aerobic or anaerobic conditions, two types of silver nanoparticles, named AgNPs-EPSaer and the AgNPs-EPSanaer, were produced respectively. The effects on bacterial cells was demonstrated by using Escherichia coli K12 and Kocuria rhizophila ATCC 9341 (ex Micrococcus luteus) as Gram-negative and Gram-positive tester strains, respectively. The best antimicrobial activity was observed for AgNPs-EPSaer, in terms of minimum
inhibitory concentrations and minimum bactericidal concentrations. Observations by transmission electron microscopy showed that the cell morphology of both
tester strains changed during the exposition to AgNPs-EPSaer. In particular, an electron-dense wrapped lament was observed in E. coli cytoplasm after 3 h of AgNPs-EPSaer exposition, apparently due to silver accumulation in DNA, and both E. coli and K. rhizophila cells were lysed after 18 h of exposure to AgNPs-EPSaer. The DNA breakage in E. coli cells was conrmed by the comparison of 3-D uorescence spectra ngerprints of DNA. Finally the accumulation of silver on DNA of E. coli was conrmed directly by a signicant Ag? release from DNA, using the scanning electrochemical microscopy and the voltammetric determinations.
Keywords Antimicrobial activity Cell lysis Silver
exopolysaccharide nanoparticles Silver in DNA
Silver release
Electronic supplementary material The online version of this article (doi:http://dx.doi.org/10.1007/s10534-016-9918-4
Web End =10.1007/s10534-016-9918-4 ) contains supplementary material, which is available to authorized users.
F. Baldi (&) S. Daniele M. Gallo S. Paganelli
Dipartimento di Scienze Molecolari e Nanosistemi, University C Foscari of Venice, Via Torino 155, 30172 Venice, Italye-mail: [email protected]
D. BattistelDipartimento...