Disruption of biofilm formation by fractions from book gills and carapace of horseshoe crab Tachypleus gigas

Horseshoe crabs have survived for a long period due to their myriad defence mechanism. Thorough studies were conducted on their adaptive defence mechanisms but few highlighted their primary innate defence. This study aimed to determine the antifouling properties of the methanolic crude extracts and fractions obtained from the book gills and carapace of the Tachypleus gigas and to characterize their bioactive metabolites, using the detachment and preventive measurements. The active fractions recovered from the recycling HPLC were further analysed using GC-MS and major active constituents were identified. The results obtained indicated that the extract and fractions of T. gigas had significant detachment mode of actions for antifouling activities. Chemical interactions such as synergistic effects were observed in both the book gills and the carapace. Chemical profiles indicated the presence of organic acids such as amino acid, simple sugars and fatty acids. The observed activities might be caused by nutrient-induced biofilm dispersion mechanisms. These findings may provide new insight into the defence mechanism of the horseshoe crabs against biofilm formation. The isolated active fractions and the identified molecules from the horseshoe crab T. gigas may be applied as a dispersal antifouling agents. Further studies are needed to confirm these prospective potential applications.