Antifouling Lipids from Marine Fungi of the Beibu Gulf.

Background

The search for environmentally friendly antifouling agents has led to an increased focus on marine natural products.

Methods

This study investigated the antifouling potential of lipid fractions extracted from ten marine fungal strains isolated from the Beibu Gulf, China. The lipids were evaluated through a multi-level bioassay approach, including the inhibition of microfouling (against four fouling bacteria: Marinobacterium jannaschii, Vibrio pelagius, Vibrio rotiferianus, and Alteromonas macleodii), the prevention of macrofouling (inhibition of barnacle Amphibalanus reticulatus cyprid settlement), and long-term (90-day) marine field trials.

Results

Eight lipid fractions demonstrated inhibitory effects against at least one bacterial strain. Five lipids significantly inhibited barnacle cyprid settlement, with half-maximal effective concentration (EC50) values ranging from 0.21 to 1.81 µg/mL and exhibited low toxicity (half-maximal lethal concentration (LC50) > 50 µg/mL). Notably, four lipid fractions maintained potent antifouling efficacy (>70% inhibition) throughout the 90-day field exposure. Chemical characterization via gas chromatography-mass spectrometry (GC-MS) revealed that the bioactive fractions were predominantly composed of fatty acids and their derivatives. Major identified compounds included palmitic acid, methyl palmitate, linoleic acid, dodecyl-9-ynyl chloroacetate, cis-13-octadecenoic acid, oleic acid, methyl 11,14-octadecadienoate, and (E)-9-octadecenoic acid methyl ester.

Conclusions

This work represents the first comprehensive investigation of marine fungal lipids from the Beibu Gulf with multi-target antifouling properties, providing a theoretical foundation and practical candidate compounds for developing eco-friendly antifouling coatings.