2-Phenylethanol in Endophytes of Areca Catechu L. Inhibits the Biofilms and Virulence Against Aeromonas Hydrophila

Objective: Aeromonas hydrophila (A. hydrophila) can cause many infectious diseases, and its biofilms and virulence are an important reason for the infection in clinical. Natural inhibitors can inhibit biofilm formation and virulence production of bacteria, thereby reducing pathogenicity and infection. Materials and Methods: The inhibitory effect of 2-phenylethanol (isolated from Streptomyces cyaneochromogenes RC1 of Areca catechu L.) on A. hydrophila biofilm formation was assessed using crystal violet staining and scanning electron microscopy (SEM). The compound was tested at subinhibitory concentrations (below the MIC of 2 mg/mL). The inhibition rates of extracellular polymeric substances (EPS), hemolytic activity, and bacterial motility were measured at 1/2 MIC (1 mg/mL). Metabolomic profiling was performed to evaluate the impact of 2-phenylethanol on A. hydrophila intracellular metabolism. Key metabolic pathways, including amino acid metabolism (tryptophan, glutamine), nucleotide metabolism, ATP-binding cassette (ABC) transporters, and lipopolysaccharide biosynthesis, were analyzed. Results: 2-Phenylethanol significantly inhibited A. hydrophila biofilm formation at subinhibitory concentrations. Crystal violet and SEM analysis confirmed the inhibitory effect, with a 40.9% reduction in biofilm formation at 1/2 MIC (1 mg/mL). Extracellular polymeric matrix (EPS) production was reduced by 51.1%, 72.2%, and 54.0% at 1/2 MIC of 2-phenylethanol, respectively. Metabolomic analysis revealed that 2-phenylethanol disrupted intracellular metabolism, particularly affects amino acid metabolism (tryptophan, glutamine pathways), Nucleotide metabolism, ATP-binding cassette (ABC) transporters, and Lipopolysaccharide biosynthesis. Conclusion: This study may provide a more theoretical basis for the treatment of A. hydrophila infection with 2-phenylethanol.