Lavender compounds interfere with AI-2 dependent bioluminescence in Vibrio harveyi without affecting LuxS signaling in Campylobacter jejuni.

Bacterial intercellular communication is essential for biofilm formation. The interspecies signaling molecule autoinducer-2 (AI-2), produced by LuxS, is involved in Campylobacter jejuni intercellular signaling, metabolism, motility, virulence, and biofilm formation, although its receptor remains unidentified. We studied the effects of lavender preparations (essential oil and ethanol extracts of Lavandula angustifolia) and pure compounds (linalool and linalyl acetate) on the signaling mechanisms in C. jejuni. Using the Vibrio harveyi MM30 biosensor, we observed a significant reduction in bioluminescence following treatment with lavender-derived compounds. A C. jejuni 11168ΔluxS mutant was included as a negative control to distinguish effects on AI-2 production from interference with biosensor detection. AI-2 concentrations measured by HPLC-FLD remained unchanged. In addition, luxS expression (qPCR) and LuxS protein abundance (orbitrap-based mass spectrometry) were unaffected. The decreased bioluminescent response despite unaltered AI-2 concentrations indicates interference with AI-2 detection rather than production, a hypothesis further explored in silico. These findings highlight the complexity of AI-2 signaling and suggest lavender compounds as potential modulators of bacterial communication.