Polysaccharide-based silver nanoparticles synthesized by Klebsiella oxytoca DSM 29614 cause DNA fragmentation in E. coli cells

Anna Maria Puglia, Giuseppe Gallo, Dario Battistel, Salvatore Daniele, Michele Gallo, Claudia Faleri, Oreste Piccolo, Stefano Paganelli, Franco Baldi

Risultato della ricerca: Articlepeer review

25 Citazioni (Scopus)


Silver nanoparticles (AgNPs), embedded into a specific 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 filament 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 confirmed by the comparison of 3-D fluorescence spectra fingerprints of DNA. Finally the accumulation of silver on DNA of E. coli was confirmed directly by a significant Ag+ release from DNA, using the scanning electrochemical microscopy and the voltammetric determinations.
Lingua originaleEnglish
pagine (da-a)321-331
Numero di pagine11
Stato di pubblicazionePublished - 2016

All Science Journal Classification (ASJC) codes

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