In vitro antibiofilm activity of the melanin from Auricularia auricula, an edible jelly mushroom

A melanin derived from Auricularia auricula was characterized based on ultraviolet-visible (UV), infrared (IR), electron paramagnetic resonance (EPR) spectra and chemical tests. The antibiofilm activity of the isolated A. auricula melanin against Escherichia coli K-12, Pseudomonas aeruginosa PAO1 and P. fluorescens P-3 was examined using crystal violet and LIVE/DEAD BacLight staining as well as confocal laser scanning microscopy (CLSM). The results showed that A. auricula melanin could inhibit significantly biofilm formation of E. coli K-12, P. aeruginosa PAO1 and P. fluorescens P-3, while no inhibitory effects on growth were found. CLSM analysis showed that A. auricula melanin treatment resulted in thinner and looser biofilm compared with the control. The current study reveals for the first time the antibiofilm activity of melanin derived from A. auricula.