Mechanistic aspects of biologically synthesized silver nanoparticles against food- and water-borne microbes

Abstract

In the present study, silver nanoparticles (AgNPs) synthesized from aqueous leaves extract of Malva crispa and their mode of interaction with food- and water-borne microbes were investigated. Formation of AgNPs was conformed through UV-Vis, FE-SEM, EDS, AFM, and HR-TEM analyses. Further the concentration of silver (Ag) in the reaction mixture was conformed through ICP-MS analysis. Different concentration of nanoparticles (1-3 mM) tested to know the inhibitory effect of bacterial pathogens such as Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Salmonella typhi, Salmonella enterica and the fungal pathogens of Penicillium expansum, Penicillium citrinum, Aspergillus oryzae, Aspergillus sojae and Aspergillus niger. Interestingly, nanoparticles synthesized from 2 to 3 mM concentration of AgNO3 showed excellent inhibitory activities against both bacterial and fungal pathogens which are well demonstrated through well diffusion, poison food technique, minimum inhibitory concentration (MIC), and minimum fungicidal concentration (MFC). In addition, mode of interaction of nanoparticles into both bacterial and fungal pathogens was documented through Bio-TEM analysis. Further the genomic DNA isolated from test bacterial strains and their interaction with nanoparticles was carried out to elucidate the possible mode of action of nanoparticles against bacteria. Interestingly, AgNPs did not show any genotoxic effect against all the tested bacterial strains which are pronounced well in agarose gel electrophoresis and for supporting this study, UV-Vis and Bio-TEM analyses were carried out in which no significant changes observed compared with control. Hence, the overall results concluded that the antimicrobial activity of biogenic AgNPs occurred without any DNA damage.

Biosynthesis of silver nanoparticles formation from Caesalpinia pulcherrima stem metabolites and their broad spectrum biological activities

“…Best particle formation occurred at pH 10. Using alkaline pH for AgNPs synthesis is also reported by [22].…”

A Systematic Review of the Genotoxicity and Antigenotoxicity of Biologically Synthesized Metallic Nanomaterials: Are Green Nanoparticles Safe Enough for Clinical Marketing?

“…Table S1 provides data on the in vitro genotoxic effects of biogenic NPs for each biological source used to synthesize MNPs and Table S2 shows the in vivo genotoxicity outcomes. Although several studies reported no genotoxicity [24,25,26,27,28,29,30,31,32] or antigenotoxic activity [24,33,34,35,36] of biogenic MNPs, most of the studies reported genotoxic effects at specific concentrations and with a dose or time dependence.…”

Malva: Food, Medicine and Chemistry

“…Synthesis of nanoparticles of precious metals (or their oxides) using Malva species extracts has been reported by many groups. [140][141][142]172,188,216,[303][304] In all these reports, aqueous extracts of leaves or flowers of the plants were used. The major quality that enables this kind of uses and reactions is the fact that these extracts are rich in flavonoids and anthocyanins.…”

“…These were tested against various pathogen bacteria and found effective. 141 They were also highly toxic for zebra fish (Danio rerio) 142 …”