Inhibition effect of marine active peptides SF on dual-species biofilms of Vibrio parahaemolyticus and Aeromonas sobria

To mitigate food contamination caused by multi-species biofilms, the inhibitory effect of peptide SF on dual-species biofilms was investigated in the study. Vibrio parahaemolyticus frequently engages in intercommunication with other bacteria through the autoinducer-2 (AI-2)/LuxS quorum sensing system, contributing to the biofilm formation. However, the knowledge of quorum sensing inhibitors (QSIs) that target dual-species biofilms involving V. parahaemolyticus has remained limited. Therefore, this study constructed dual-species biofilms of V. parahaemolyticus and Aeromonas sobria, assessed AI-2 activity, and investigated the inhibitory effect of the QSI peptide Ser-Phe (SF) on these biofilms. The results indicated that peptide SF (1 mg/mL) significantly inhibited AI-2 activity, production of extracellular polysaccharides, proteins, DNA, metabolic activity, hydrophobicity, and auto-aggregation of these biofilms. The inhibitory rates to the both dual-species and V. parahaemolyticus mono-species were 44.40% and 47.31% for AI-2 activity, 31.29% and 63.84% for extracellular polysaccharides, 53.64% and 48.61% for extracellular proteins, 55.38% and 52.58% for extracellular DNA, 46.18% and 24.46% for metabolic activity, 67.46% and 50.61% for hydrophobicity, and 44.15% and 51.98% for auto-aggregation. Moreover, scanning electron microscopy revealed the disruption of the structure in dual-species biofilms treated with peptide SF. The qRT-PCR results demonstrated that peptide SF down-regulated the expression of key genes related to quorum sensing (luxS and luxP), flagellum (flaA), virulence factors (toxR), and extracellular polymeric substances (cpsA) in the dual-species. However, peptide SF did not inhibit AI-2 activity or biofilm formation in A. sobria. This study will provide a QSI for controlling multi-species biofilms caused by V. parahaemolyticus.