Biosynthesis of Crystalline Silver and Gold Nanoparticles by Extremophilic Yeasts

Abstract

The biosynthesis of Ag and Au nanoparticles (NPs) was investigated using an extremophilic yeast strain isolated from acid mine drainage in Portugal. Three distinct studies were performed, namely, the growth of yeast strain in presence of metal ions, the use of yeast biomass for the metal nanoparticles synthesis, and of the supernatant obtained after 24-hour incubation of yeast biomass in water. The extremophilic strain under study was able to grow up to an Ag ion concentration of 1.5 mM whereas an increase of Au ion concentration over 0.09 mM caused a strong inhibitory effect. A successful route for the metal NPs synthesis was obtained using the yeast biomass. When the washed yeast cells were in contact with Ag or Au solutions, AgNPs smaller than 20 nm were produced, as for the AuNPs diameter ranged from 30 to 100 nm, as determined through transmission electron microscopy and confirmed by energy-dispersive X-ray spectra. The supernatant-based strategy provided evidence that proteins were released to the medium by the yeasts, which could be responsible for the formation and stabilisation of the Ag NPs, although the involvement of the cell wall seems fundamental for AuNPs synthesis.

Antimicrobial activity of biogenic silver nanoparticles, and silver chloride nanoparticles: an overview and comments

“…The same results were reported from yeast strain from an acid mine drainage in Portugal (Mourato et al 2011), and from yeast species (strain MKY3), which were isolated from garden soil (Kowshik et al 2003).…”

Comparative study of MnO2 nanoparticle synthesis by marine bacterium Saccharophagus degradans and yeast Saccharomyces cerevisiae

“…Microscopic observations of solutions of MnO 2 NPs revealed the presence of S. cerevisiae cells in the method of tea bags but not in the method of dialysis membranes. Proteins released by yeast cells have been reported to play an important role in the synthesis of silver nanoparticles, whereas the cell wall was involved in the synthesis of gold nanoparticles (Mourato et al 2011). The tests with BSA as a protein representative showed positive reactions, indicating the possible role of proteins released by S. cerevisiae for extracellular MnO 2 NP synthesis.…”

“…The syntheses of nanoparticles using biological methods have captured considerable interest in modern nanoscience and technology due to their flexibility, biocompatibility, and eco-friendly nature (Borase et al 2014). Plants, algae, lichen, bacteria, actinomycetes, yeasts, and filamentous fungi have been used for the synthesis of different types of nanoparticles (Ahmad et al 2003;Saif et al 2008;Mourato et al 2011;Rai et al 2011;Salunkhe et al 2011;Castro et al 2013;Mie et al 2014;Salunke et al 2014a, b).…”

Biogenic Synthesis of Nanoparticles and Potential Applications: An Eco- Friendly Approach

“…The synthesis of cadmium nanoparticles by using Candida glabrata and Schizosaccharomyce pombe has been reported by Dameron et al [49]. The silver and gold nanoparticles biosynthesis was also investigated by Mourato et al [50], using an extremophilic yeast strain isolated from acid mine drainage. The marine yeast Rhodosporidium diobovatum has been explored for intracellular synthesis of stable lead sulfide nanoparticles [51].…”