The effects of bacteria-nanoparticles interface on the antibacterial activity of green synthesized silver nanoparticles

Minimum bactericidal concentration of chemically synthesized silver nanoparticles against pathogenic Salmonella and Shigella strains isolated from layer poultry farms

“…AgNPs have the ability to attach and destruct bacterial cell walls in a dosedependent manner (Cerny and Teuber, 1971;Rhayour et al, 2003;Ahmad et al, 2017) this is confirmed by Electron spin resonance spectroscopy studies which demonstrated that when AgNPs attached to the bacterial cell walls, the free radicals of the AgNPs were then released (Danilcauk et al, 2006;Kim et al, 2007;Swarnavalli et al, 2017).…”

“…The AgNPs bactericidal properties are attributed mainly to their following abilities: bacterial cell walls and membrane destruction, reactive oxygen species (ROS) generation, vital metabolic enzyme inhibition, and obstruction of DNA replication (Feng et al, 2000;Sondi and Salopek-Sondi, 2004;Kim et al, 2007;Rai et al, 2009;Ahmad et al, 2017). AgNPs have the ability to attach and destruct bacterial cell walls in a dosedependent manner (Cerny and Teuber, 1971;Rhayour et al, 2003;Ahmad et al, 2017) this is confirmed by Electron spin resonance spectroscopy studies which demonstrated that when AgNPs attached to the bacterial cell walls, the free radicals of the AgNPs were then released (Danilcauk et al, 2006;Kim et al, 2007;Swarnavalli et al, 2017).…”

“…These released free radical seems to be the main causative agent responsible for final bacterial destruction and death (Devi et al, 2017); as these free radicals begin to make pores in the bacterial cell walls and membranes causing severe permeability of the bacterial cell membrane (Danilcauk et al, 2006;Kim et al, 2007;Swarnavalli et al, 2017), this is followed by releasing of periplasmic proteins and nucleic acids via cytoplasmic membrane, and so the bacterial cell death will be the final result (Cerny and Teuber, 1971;Rhayour et al, 2003;Ahmad et al, 2017;Swarnavalli et al, 2017). On the other hand, when AgNPs enter the bacterial cell, they form a low molecular weight region which begin to attack the respiratory chain, so consequently, the cellular signaling pathways will be changed by dephosphorylating assumed key peptide substrates on tyrosine residues (Sondi and Salopek-Sondi, 2004;Mulley et al, 2014;Su et al, 2017b).…”

“…Moreover, the Ag+ metal ions that released from AgNPs (Feng et al, 2000;Swarnavalli et al, 2017) were found to have obstructing behavior to the bacterial signal transduction pathways (Devi et al, 2017) and moreover they could react with thiol groups present in the bacterial vital enzymes and proteins (Matsumura et al, 2003;Swarnavalli et al, 2017;Su et al, 2017b;Gopinath et al, 2016) and furthermore, they could react with phosphorus-containing compounds like DNA leading to inhibition of bacterial DNA replication, and so the bacterial cell death will be the final result (Jiao et al, 2014;Bao et al, 2015;Su et al, 2017b;Devi et al, 2017). On the other hand, the production of intracellular reactive oxygen species (ROS) by AgNPs occurred via the reaction between the AgNPs with the thiol-containing enzymes of the bacterial respiratory chain (Matsumura et al, 2003;Ahmad et al, 2017). The ROS seems to another causative agent responsible for final bacterial destruction and death (Shrifian-Esfahni et al, 2015;Ahmad et al, 2017) as this ROS is cytotoxic fatal to the bacterial cell in dose and surface charge dependent manner (Ahmad et al, 2017).…”

“…The nanoparticles size and surface area are significant agents to which their bactericidal mechanism of action attributed to (Devi et al, 2017). Silver nanoparticles (AgNPs) has been gaining importance in recent years due to their broad spectrum bactericidal toxic effects against broad spectrum pathogenic bacteria (Ahmad et al, 2017) even at their minimum concentrations (Devi et al, 2017). Furthermore, the results offered by suggest that AgNPs can be used as potent bactericidal agents against antibiotic-resistant bacteria.…”