Figure 1.

Intra-and extracellular biosynthesis of metal-nanoparticles by Bacillus spp. Extracellular biosynthesis of metal-nanoparticles is carried out by trapping metal ions on the cell surface and reducing them in the presence of secreted enzymes or metabolite and/or membrane-bound enzymes. In the intracellular biosynthesis of metal-nanoparticles, after transfer of metal ions into cell cytoplasm, the metal ions are reduced as a result of metabolic reactions with enzymes such as alpha-NADPH-dependent nitrate reductase.