Fig. 3. Melanization reaction products of P. monodon exhibit antibacterial and antifungal activities in vitro. Melanization reaction products were prepared from SHLS alone (no substrate) or SHLS with 2 mM L-DOPA, dopamine or DHI as the substrate. The (A, B) Gram-negative bacteria Vibrio harveyi and V. parahaemolyticus, respectively, the (C) Gram-positive bacteria B. subtilis, and (D) the filamentous fungus F. solani were treated with the above shrimp melanization reaction products with or without PTU, prior to further culture on LB (bacteria) or PDA (fungus) overnight and then the total viable colony number (CFUs) was evaluated. Data are shown as the mean (±1 SE), and are derived from three independent repeats. Asterisk indicates a statistical significant difference between means (P < 0.05).