Biologically synthesized silver nanoparticles, mediated by Bothriochloa laguroides, inhibit biofilm formation and eradicate mature biofilm of Yersinia enterocolitica and Staphylococcus aureus

Abstract

To phytosynthesize silver nanoparticles (AgNPs) and determine their antibacterial and antibiofilm capacity against gram-positive and gram-negative bacterial strains. AgNPs were synthesized using Bothriochloa laguroides aqueous extract as reducing and stabilizing agent. After characterization, a phytochemical screening to the extract and the AgNPs was performed. Antibacterial activity, inhibition and eradication of biofilms against Staphylococcus aureus and Yersinia enterocolitica strains were tested. Spherical AgNPs with an average size of 8 nm were obtained. Tannins, flavonoids, carbohydrates, proanthocyanidins, anthocyanins and saponins were identifiedin aqueous extract; meanwhile, only carbohydrates were identified in AgNPs. The MICand MBC were determined at pmol L−1 levels for all tested strains. Furthermore, AgNPsinhibited more than 90% of biofilms formation and eradicated more than 80% of maturebiofilms at concentrations higher than MIC. The AgNPs obtained in this study inhibited planktonic and sessile growth,and eradicated mature biofilms of pathogenic bacterial strains at very low concentrations. The current study showed the promising potential ofAgNPs as antibiofilm agents opening the way for the future development of a new classof antibacterial products.