Unraveling the anti-biofilm properties of Laurinterol on pioneer biofouling bacteria from the red seaweed Laurencia johnstonii

A biofilm is a complex microbial community, representing the initial stage in biofouling formation. Consequently, it is responsible for significant economic losses in several industrial sectors worldwide. Therefore, there is a constant need for safer and environmentally friendly coatings, particularly those derived from new marine sources such as seaweeds with antifouling properties. Red algae produce metabolites that prevent bacterial attachment and biofilm formation by disrupting microbial membranes, inhibiting quorum sensing, or interfering with extracellular matrix production, among them Laurencia johnstonii. This species has particular ecological or geographical advantages that make it more accessible or abundant for research in the Bay of La Paz, BCS. This study aimed to assess the anti-biofilm potential of the red seaweed Laurencia johnstonii. To identify bioactive compounds, the anti-biofilm activity of the ethanolic extract was evaluated against marine biofilm-forming strains: Bacillus altitudinis, Bacillus pumilus, Bacillus subtilis, and Bacillus cereus. The ethanolic extract of L. jonhstonii exhibited the highest percentage of inhibition. Subsequent chromatographic fractionation led to the isolation and identification of laurinterol, the primary compound responsible for the anti-biofilm activity (>97 %) and antibacterial activity (MIC <3.9 µg/mL). To our knowledge, this is the first report of the activity of laurinterol against biofilm-forming strains.