Nasim Gholampoor, Giti Emtiazi and Zarrindokht Emami
The Influence of Microbacterium hominis and Bacillus licheniformis Extracellular Polymers on Silver and Iron Oxide Nanoparticles Production; Green Biosynthesis and Mechanism of Bacterial Nano Production
Due to the abundant applications of metal nanoparticles on different area, researchers are always looking for fast, easy, cheap and non-toxic way to synthesis nanoparticles. In scientific communities, green and biological synthesis of nanoparticles have got more attention, so in this study 300 μl of extracellular polysaccharides (28.8717 mg/L and 35.5344 mg/L) from Microbacterium hominis and Bacillus licheniformis respectively were used to produce silver, silver oxide, iron oxide and iron metal nanoparticles from silver nitrate and iron chloride (1 mM).These strains were isolated on Caso Agar medium enriched with 20% sucrose. It was interesting that bacteria without polysaccharide could not produce these nanoparticles while the whole cells with extracellular polysaccharide do the same reaction as polysaccharides and carboxy methyl cellulose. FTIR analyzing showed these polysaccharides has similarities in structure with carboxy methyl cellulose and have certain functional groups such as hydroxyl, carbonyl, methyl and aldehyde, so the mechanism for making nanoparticles by these microorganisms is probably is not related to enzyme activities. The properties of nanoparticles were investigated by XRD, AFM and UV absorption (200-800 nm). The crystalline, approximate size and color changes were detected. Iron and iron oxide nanoparticles, was cubic structures with sizes of 29-42 nm and silver and silver oxide nanoparticles was hexagonal with 12-42 nm.
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