Biological Synthesis of Gold and Silver Nanoparticles Mediated by the Bacteria Bacillus Subtilis

Abstract

Biological synthesis of gold and silver nanoparticles was carried out using the bacteria Bacillus subtilis. The reduction processes of chloroaurate and silver ions by B. subtilis were found to be different. Gold nanoparticles were synthesized both intra- and extracellularly, while silver nanoparticles were exclusively formed extracellularly. The gold nanoparticles were formed after 1 day of addition of chloroaurate ions, while the silver nanoparticles were formed after 7 days. The nanoparticles were characterized by X-ray diffraction, UV-vis spectra and transmission electron spectroscopy. X-ray diffraction revealed the formation of face-centered cubic (fcc) crystalline gold nanoparticles in the supernatant, broth solution and bacterial pellet. Silver nanoparticles also exhibited diffraction peaks corresponding to fcc metallic silver. UV-vis spectra showed surface plasmon vibrations for gold and silver nanoparticles centered at 530 and 456 nm, respectively. TEM micrographs depicted the formation of gold nanoparticles intra- and extracellularly, which had an average size of 7.6 +/- 1.8 and 7.3 +/- 2.3 nm, respectively, while silver nanoparticles were exclusively formed extracellularly, with an average size of 6.1 +/- 1.6 nm. The bacterial proteins were analyzed by sodium dodecyl sulfonate-polyacrylamide electrophoresis (SDS-PAGE) before and after the addition of metal ion solutions. We believe that proteins of a molecular weight between 25 and 66 kDa could be responsible for chloroaurate ions reduction, while the formation of silver nanoparticles can be attributed to proteins of a molecular weight between 66 and 116 kDa. We also believe that the nanoparticles were stabilized by the surface-active molecules i.e., surfactin or other biomolecules released into the solution by B. subtilis.

Phytosynthesis of eco-friendly silver nanoparticles and biological applications A novel concept in nanobiotechnology

“…Saifuddin et al (2009) found that exposure of culture supernatanant of Bacillus subtilis with microwave irradiation to silver ions lead to the formation of AgNPs with size in the range of 5 -60 nm. Reddy et al (2010) reported that there is extensive extracellular biosynthesis of AgNPs by using the same species B. subtilis.…”

Biosurfactants and Bioemulsifiers Biomedical and Related Applications – Present Status and Future Potentials

“…More recently they also carried out a biological synthesis of gold and silver nanoparticles using the bacteria Bacillus subtilis. Gold nanoparticles were synthesized both intra-and extracellularly, while silver nanoparticles were exclusively formed extracellularly (Reddy et al, 2010). According to the Authors the nanoparticles were stabilized by the surface-active molecules i.e., surfactin or other biomolecules released into the solution by B. subtilis.…”

“…They also plan to investigate these nanoparticles suitability for medical and diagnostic applications. Recently, methodologies for the biological synthesis of metal nanoparticles using microbes have also been described (Narayanan & Sakthivel, 2010;Kalishwaralal et al, 2010;Reddy et al, 2010). In addition Smyth et al, (2010b) reported on the production of selectively deuterated rhamnolipids and sophorolipids using deuterated substrates.…”

A Novel Biological Synthesis of Gold Nanoparticle by <i>Enterobacteriaceae<i/> Family

“…The synthesizing process is low-cost and non-toxic [13,14]. The objective of this study is to demonstrate the feasibility of a bacterial/enzyme-based in vitro approach for the biosynthesis of gold nanoparticles from Enterobacteriaceae family.…”