Potential roles of succinic acid against colonization by a tubeworm

This study investigated the potential role of a fungal metabolite isolated from a sponge surface-associated fungus in a biofouling control. Succinic acid with both antibacterial and anti-larval settlement activity was isolated from the fungus associated with the sponge Acanthella cavernosa, using bioassay-guided isolation and purification procedure. Succinic acid was then embedded in hydrogel discs that were subsequently exposed to natural seawater for 24, 48 and 72 h to allow the development of biofilms on the disc surfaces. Both epifluorescence microscopy and DNA fingerprinting analysis were used for the analysis of cell density and species diversity of bacterial communities in the biofilms, respectively. The results indicated that succinic acid substantially altered the cell density and species diversity of the bacterial communities in the biofilms on hydrogel surfaces in comparison to the control hydrogel discs (without succinic acid). Laboratory larval-settlement bioassay with larvae of the fouling tubeworm Hydroides elegans showed that fewer larvae settled on the surface of hydrogel discs covered with the biofilms that had been altered by succinic acid than on the surface of the control discs. Field experiments using succinic acid-coated panels further confirmed the antifouling activity of the compound. In summary, this study provides evidence that compound(s) originated from microbes can act as effective antifouling agent.