Anti -oxidant, anti -bacterial and anti-biofilm activity of biosynthesized silver nanoparticles using Gracilaria corticata against biofilm producing K. pneumoniae

Abstract

Silver nanoparticles (Ag NPs) with anti -bacterial effects against the biofilm-producing bacteria Klebsiella pneu- moniae ( K. pneumoniae ) were synthesized using the marine seaweed Gracilaria corticata ( G. corticata ). Physiochemical characterization using UV -spectrometer, fourier transform infrared spectroscopy (FTIR) and X- ray diffraction (XRD) confirmed that the synthesized material consisted of Ag NPs. Morphological analysis using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) with energy -dispersive X-ray (EDX) analysis confirmed the shape, size, surface morphology, and available chemical composition of the Ag NPs. Furthermore, the rich phenolic and flavonoid content of G. corticata has excellent antioxidant activity, which was confirmed through gas chromatography -mass spectrometry (GC -MS) analysis. The highest anti- bacterial activity and biofilm reduction (88 %) of Ag NPs treated K. pneumoniae was observed at 50 ?g/mL and 100 ?g/mL concentrations respectively. The bacterial viability and exopolysaccharide production of K. pneu- moniae significantly decreased after treatment with Ag NPs. Morphological alterations and intracellular damage