Surface Interactions between an Eco-Friendly Antifouling Agent and Pseudoalteromonas tunicata Membrane

In this work, we investigated the interfacial chemistry of our recently developed antifouling polyphenolic small molecule (GBA26) directly with bacterial membrane models and the marine bacterium Pseudoalteromonas tunicata. Different Langmuir lipid monolayer models were constructed to mimic the interface of bacterial membranes. Surface pressure-area isotherms showed that GBA26 interacted with assembled lipid monolayers, and this interaction was influenced by the phospholipid composition. GBA26 was also able to interact with monolayers of lipopolysaccharide (LPS) extracted from P. tunicata. The morphology of the monolayer was also analyzed using Brewster angle microscopy (BAM), showing that GBA26 reduced lipid domains' condensation levels. Flow cytometry data indicated that GBA26 disrupts cell membranes and reduces the metabolic activity of P. tunicata, without inducing ROS formation. Furthermore, GBA26 significantly decreased bacterial culturability. Altogether, these results shed light on its antibiofilm mechanism against this marine bacterium.