Effect of growth phase (A) and medium (B) on AI-2 production in representative species of the genus Shewanella. (A) Comparison between a Shewanella species with low (A. fetalis) and high (S. japonica) maximum AI-2 level. (B) AI-2 levels during growth for S. hafniensis DT-1 cultivated in marine broth (MB) and in Luria Bertani medium with sea salts (LBSS). Fold induction values are given as percentage of the positive control. Standard deviations are given for 4 replicate measurements of the same sample within a bioassay.