Abstract: This study aimed to investigate the quorum sensing (QS) activity and biofilm formation of Aeromonas spp. isolated from refrigerated grass carp as the dominant spoilage organism. The QS activity was detected using the reporter strain Chromobacterium violaceum CV026, and the biofilm formation was quantified by staining method. Then the effect of temperature and QS signaling molecules on the biofilm formation was explored. The results showed that the isolated Aeromonas spp. contained a plurality of species, and 90% of the 20 isolates could secret acyl-homoserine lactones (AHLs). Two strains of A. salmonia W41 and A. salmonia W69 with strong biofilm formation ability were chosen for further analysis. The results indicated that the biofilm formation ability of the two strains was significantly higher at 30 ℃ and 8 ℃ than at 37 ℃. Both strains mainly produced N-butanoyl-L-homoserine lactone (C4-HSL) and N-hexanoyl-L-homoserine lactone (C6-HSL) signaling molecules. The biofilm formation of W41 was significantly promoted by 50 μmol/L C6-HSL. Low concentrations of C4-HSL and C6-HSL promoted the biofilm formation of W69, but high concentrations of C4-HSL and C6-HSL had an inhibitory effect. The present study exhibited that most Aeromonas spp. showed QS phenomenon, and the biofilm formation of Aeromonas spp. was affected not only by individual differences and temperature, but also by the concentration and type of QS signaling molecules.

Key words: Ctenopharyngodon idellus, Aeromonas spp., quorum sensing, biofilm