Presentation Information
[P02-223]Biogenic Metal Nanoparticles Produced by an Environmental Isolate of Shewanella sp. via Microbial Bioreduction
○Chih-Ching Chien1, Long-Yi Wu1 (1. Yuan Ze Universoty (Taiwan))
Keywords:
Metal nanoparticles,Microbial bioreduction,Shewanella
Metal nanoparticles have attracted considerable attention because of their broad applications in industry, environmental technology, and biomedicine. Their high surface area-to-volume ratio enhances catalytic activity, chemical reactivity, and functional versatility, making them useful in drug delivery, biosensing, antimicrobial agents, electronics, and environmental remediation. Conventional production methods, including physical and chemical synthesis, often require toxic reagents, high temperatures, and high pressures, leading to environmental and safety concerns. Therefore, environmentally friendly and sustainable alternatives for nanoparticle synthesis are highly desirable.
Biological synthesis has emerged as a promising green approach for metal nanoparticle production. Various microorganisms can reduce metal ions into nanoparticles under mild conditions. Among them, bacteria of the genus Shewanella are particularly notable due to their versatile respiratory metabolism and ability to reduce a wide range of metal ions through enzymatic and electron transfer mechanisms. These properties enable Shewanella species to precipitate metal nanoparticles either intracellularly or extracellularly via bioreduction or adsorption processes.
In this study, a Gram-negative bacterium capable of reducing metal ions was isolated from sediment samples and identified as Shewanella sp. based on 16S rRNA gene sequence analysis. The isolate was designated strain ACH-1. Its tolerance to and reduction of gold and copper ions were investigated. The bacterium was able to grow in Luria–Bertani (LB) medium containing gold (as HAuCl4, 50–200 ppm) or copper (as CuSO4, 50–500 ppm), demonstrating substantial resistance to both Au3+ and Cu2+.
Metal reduction experiments demonstrated marked decreases in soluble metal concentrations following incubation with strain ACH-1. Upon exposure to a high concentration of Au3+, the gold levels dropped dramatically to a small fraction of the initial amount. Likewise, Cu2+ supplied at a moderate concentration was reduced to nearly half of its starting level. These findings confirm active metal bioreduction and strongly suggest the formation of nanoparticles. Transmission electron microscopy further verified the intracellular accumulation of electron-dense metal nanoparticles within the bacterial cells.
Overall, these findings demonstrate that Shewanella sp. strain ACH-1 can tolerate and reduce gold and copper ions, leading to intracellular nanoparticle formation under environmentally benign conditions. This study highlights the potential of sediment-derived Shewanella strains as sustainable biofactories for the green synthesis of metal nanoparticles. Future work will focus on characterizing the properties and applications of the biogenic nanoparticles produced by this strain.
Biological synthesis has emerged as a promising green approach for metal nanoparticle production. Various microorganisms can reduce metal ions into nanoparticles under mild conditions. Among them, bacteria of the genus Shewanella are particularly notable due to their versatile respiratory metabolism and ability to reduce a wide range of metal ions through enzymatic and electron transfer mechanisms. These properties enable Shewanella species to precipitate metal nanoparticles either intracellularly or extracellularly via bioreduction or adsorption processes.
In this study, a Gram-negative bacterium capable of reducing metal ions was isolated from sediment samples and identified as Shewanella sp. based on 16S rRNA gene sequence analysis. The isolate was designated strain ACH-1. Its tolerance to and reduction of gold and copper ions were investigated. The bacterium was able to grow in Luria–Bertani (LB) medium containing gold (as HAuCl4, 50–200 ppm) or copper (as CuSO4, 50–500 ppm), demonstrating substantial resistance to both Au3+ and Cu2+.
Metal reduction experiments demonstrated marked decreases in soluble metal concentrations following incubation with strain ACH-1. Upon exposure to a high concentration of Au3+, the gold levels dropped dramatically to a small fraction of the initial amount. Likewise, Cu2+ supplied at a moderate concentration was reduced to nearly half of its starting level. These findings confirm active metal bioreduction and strongly suggest the formation of nanoparticles. Transmission electron microscopy further verified the intracellular accumulation of electron-dense metal nanoparticles within the bacterial cells.
Overall, these findings demonstrate that Shewanella sp. strain ACH-1 can tolerate and reduce gold and copper ions, leading to intracellular nanoparticle formation under environmentally benign conditions. This study highlights the potential of sediment-derived Shewanella strains as sustainable biofactories for the green synthesis of metal nanoparticles. Future work will focus on characterizing the properties and applications of the biogenic nanoparticles produced by this strain.
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