Figure 1.

Discoloration of bacterial culture supernatant due to AgNO₃ reduction. Reduction of silver ions by Bacillus pumilus, B. persicus, and B. licheniformis extracellular agents, as evidenced by color change of culture supernatant from yellow to dark brown. The control flasks (A) contain cell-free filtrates without silver nitrate and flasks (B) contain cell-free filtrates with silver nitrate. The yellowish color of the reaction mixtures turned to brown within 24 h of incubation in dark.