Antibacterial action of green silver nanoparticles with Staphylococcus aureus and Escherichia coli: membrane interaction.

FERREYRA MAILLARD, ANIKE PV; DALMASSO, PABLO R; HOLLMANN A

Congreso; Primeras Jornadas Virtuales SAB 2020; 2020

Sociedad Argentina de Biofisica

Silver nanoparticles (AgNPs) have proven to be an alternative for the development ofnew antibacterial agents. In this sense, the possibility to generate AgNPs coated withnovel capping agents, such as phytomolecules obtained via a green synthesis (G-AgNPs)has attracted great attention.Recently, we showed that membrane interactions are involved in the antibacterialactivity of G-AgNPs obtained using aqueous leaf extract of chicory (Cichorium intybus L.).Although the mechanism of antibacterial action has not yet been fully elucidated, dataobtained suggest a multi-step mechanism including, membrane disruption.The objective of this work was to continue the characterization of the antibacterial actionof G-AgNPs against Escherichia coli and Staphylococcus aureus. To evaluate theinhibitory effect, the growth curve of both bacteria in presence of G-AgNPs, and the killindex after 1 h of incubation were obtained. Membrane permeabilization and kinetics ofthe disruption induced by G-AgNPs on both bacteria were also analyzed. Finally, asoxidative stress induced by Ag ions was also postulated as a way of action of severalAgNPs, the effect of the antioxidant glutathione (GSH) was tested.The results obtained show that both bacteria exhibit the same MIC (10 pM) but a highereffect on E. coli was observed in short incubation times, with a kill index of 80% after 1 husing a 2 x MIC G-AgNPs concentration. The G-AgNPs induce damage in the outermembrane of E. coli and plasmatic membrane of S. aureus. Finally, when G-AgNPs wereincubated with bacteria in the presence of GSH, no lethal effects were observed neitherin E. coli nor S. aureus. Furthermore, the ability of G-AgNPs to damage the bacterialmembrane also disappears. The results of pretreatment of the GSH with G-AgNPssuggests a direct effect of GSH on the G-AgNPs. Overall, the results obtained reinforcethat AgNPs obtaining by green synthesis represents a promising approach in novelantibacterial technologies.