Effect of Forsythia suspensa extract on quorum sensing system of Aeromonas hydrophila

Abstract:

[Background] The new antimicrobial agents based on the quorum sensing system control was rapidly developed due to the multiple drug resistance caused by traditional antimicrobial agents. [Objective] To study the effect of Forsythia suspensa extract (FSE) on quorum sensing system in Aeromonas hydrophila and provide useful information for bacteria control. [Methods] The minimal inhibitory concentration (MIC) of FSE against Chromobacterium violaceum CV026 and A. hydrophila was determined by multiple dilution method, and the effects of FSE on the growth, swarming motility and protease activity of A. hydrophila were determined by micro-method. The primary components of the extracts were analyzed by high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). The possible inhibiting mechanism of FSE on the quorum sensing system of A. hydrophila was explored by molecular docking. [Results] The MICs of FSE against C. violaceum 026 and A. hydrophila were both 16.00 mg/mL. Under sub-MIC concentration, and the production of violacein was significantly inhibited by the FSE, with the maximum inhibition rate of 56.30%. The swarming mobility and protease activity of A. hydrophila was reduced by 85.70% and 35.40% with 8.00 mg/mL FSE treatment, respectively. The major components of the FSE included forsythia, forsythioside, caffeic acid and chlorogenic acid, etc. The molecular docking results indicated that caffeic acid and chlorogenic acid could competitively bind with LasR receptor protein to inhibit the quorum sensing system of A. hydrophila. [Conclusion] FSE could be used as a potential quorum sensing inhibitor in the aquaculture and biological control area.

Key words:Forsythia suspensa extract;Aeromonas hydrophila;quorum sensing;biological control