FIGURE 5.

Silver reduction and nanoparticle formation by the filtrate or retentate of the spent growth medium of A. niger cultivations. (A) Determination of the relative reduction capacity. (B) Formation of silver nanoparticles in filtrate and retentate. Absorption at 430 nm indicates the production of uncoagulated silver nanoparticles. The medium contained ammonium as the nitrogen source. All reactions were carried out at room temperature. Error bars represent standard deviation from three replicates.