Chemical reduction is the most frequently applied method for the preparation of silver nanoparticles as stable, colloidal dispersions in water or organic solvents. Commonly used reductants are borohydride, citrate, ascorbate, and elemental hydrogen. The reduction of silver ions (Ag+) in aqueous solution generally yields colloidal silver with particle diameters of several nanometers. The large scale synthesis of silver nanomaterial by chemical method suffers from issues such as polydispersity and stability, especially if the reduction is carried out in aqueous media.
The extracellular biological synthesis of AgNPs could be an attractive and ecologically friendly alternative method for the preparation of large quantities because it offers the advantage of easy downstream processing. Moreover, bacteria are easy to handle and can be manipulated genetically without much difficulty. Considering these advantages, microbial synthesis could prove to be an excellent alternative for the extracellular synthesis of AgNPs. The present work involves synthesis of silver nanoparticles by three methods and further evaluating the antimicrobial activity of these biologically synthesized nanoparticles.