Green Synthesis of Silver Nanoparticles from Energy Cane Bagasse Hydrolysate: Antimicrobial and Antibiofilm Properties

The green synthesis of silver nanoparticles (AgNPs) and their applications have gathered great attention as these nanoparticles can be used effectively in targeting microorganisms due to their antimicrobial properties. In this study, the reducing and capping potential of polyphenols extracted from energy cane bagasse was investigated in the green synthesis of AgNPs without the external addition of reducing agents. The reddish color formation and peak appearance at 430 nm were indications of the successful synthesis of the AgNPs. The synthesized nanoparticles and reducing biomolecules were further characterized by microscopy (SEM, TEM) and spectroscopy (FTIR-ATR, EDS, XRD) techniques indicating nanoparticles of spherical shape, with particle sizes averaging ~ 15 nm and surface charge of −24.8 mV. The antimicrobial activity of the synthesized nanoparticles was evaluated against several microbial species, Listeria monocytogenes ATCC 19115, Staphylococcus aureus ATCC 12600, Salmonella enterica ATCC 13312, Pseudomonas syringae ATCC BAA 871, Escherichia coli ATCC 35218, and two strains isolated from sugarcane crusher juice, Leuconostoc mesenteroides (A17) and Leuconostoc pseudomesenteroides (A25). The synthesized nanoparticles showed biocidal activity against the bacteria which was further confirmed by microscopy techniques. The cell and nanoparticles are interacting with the cell surface of microorganisms, penetrating the cell, and causing the disruption of intracellular organelles. These nanoparticles also prevented the growth of microbial biofilms. A biofilm is a complex and functional community of microbes encased in a primarily polysaccharide matrix, which acts as a barrier to protect microbes against most antimicrobials.