Abstract: The inhibitory activity of methanol extract from Spirulina platensis on quorum sensing in the mini-Tn5 mutant Chromobacterium violaceum CV026 was investigated. The violacein and biofilm production in CV026 and Shewanella spp. were also measured. The results indicated that 75% methanol extract from Spirulina platensis not only significantly reduced violacein production and biofilm formation at a concentration of 0.125－1.000 g/100 mL, but also inhibited violacein production induced by exogenous N-hexanoyl homoserine lactone (10 μmol/L C6-HSL). The inhibitory rates of methanol extract at the dose of 1.000 g/100 mL on violacein production and biofilm formation were 87.67% and 77.05%, respectively (P ＜0.05). The growth of CV026 was not affected by methanol extract at a concentration of 0.125－1.000 g/100 mL, indicating the reduction of CV026 on violacein was due to HSL-induced quorum sensing but not the inhibitory growth of CV026. In conclusion, methanol extract from Spirulina platensis can significantly inhibit bacterial quorum sensing activity, and can therefore used as an bacterial quorum sensing inhibitor for the storage of fresh and processed food.

Key words: Spirulina platensis, quorum sensing inhibition, N-hexanoyl homoserine lactone (C6-HSL)