School of Environmental Sciences, University of Venda, Private Bag X5050, Thohoyandou 0950, South Africa
This study reports a novel eco-friendly biosynthesis of Silver Nanoparticles (AgNPs) from Exopolysaccharides (EPS) of Lentinus edodes after an attempt to optimise the production of EPS through mutagenesis. It further describes some potential application of silver nanoparticles in water treatment.
A wild strain of L. edodes was subjected to UV irradiation, a physical mutagen, at 254 nm. The wild and resultant irradiated strains were then assessed for the production of EPS and subsequent application of the crude EPSs for biosynthesis of AgNPs. The particles were characterised by colour pattern and UV-visible spectroscopy. Based on superior EPS production and nanoparticle attributes, nanoparticles obtained from UV irradiated process were further subjected to Scanning Electron Microscopy (SEM). EPS produced was quantified by the phenol-sulphuric acid method and studied by GC-MS.
Results obtained for EPS productivity indicated the presence of monomer sugars such as arabinose (50.65%), mannose (19.20%), mannitol (15.58%), fructose (7.96%), trehalose (6.49%), and glucuronic acid, xylose, galactose and glucose with low percentages of ≤ 0.11. EPS productivity of wild and mutant strains was obtained as 1.044 and 2.783 mg/ml, respectively, after 7 days of fermentation. The result of EPS production for UV irradiated strain corresponds to a yield improvement of 2.7 fold of the wild-type. UV Spectroscopy and SEM analysis studies on EPS nanoparticle product of the improved (UV irradiated) strain indicated the formation of AgNPs at the absorption band of 421 nm with a size range of 50-100 nm.
This study, which aimed at eco-friendly synthesis of myco-nanoparticle has established the novel ability of L. edodes’ polysaccharide in silver nanoparticles biosynthesis. It expounded potential frontiers of silver nanoparticles application in the water industry. To the best of the authors’ knowledge, this result represents the first report on the biosynthesis of AgNPs using L. edode’s EPS.
Keywords: AgNPs, EPS, Mutants, L. edodes, UV irradiation, Myco-nanoparticle.
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