Table 1.

AI-2 activity of CM experienced by MDAI2 luxScells

CM (+AI-2 or −AI-2)Fold AI-2 activitya
CM stock solutions
 CM generated from W3110luxS+1,520
 CM generated from MDAI2luxS5
Experimental samples
 MDAI2 cells at an OD600 of 1.07
 MDAI2 cells (control, t = 0 min)6
 MDAI2 cells (exp, t = 0 min)1,498
 MDAI2 cells (control, t = 20 min)b5
 MDAI2 cells (exp, t = 20 min)b1,514
  • a Fold AI-2 activity represents the induction of luminescence (RLU) in V. harveyi reporter strain BB170 (sensor 1, sensor 2+) fromE. coli cell-free culture samples in relation to luminescence (RLU) with fresh medium alone. Values are reported as the averages of three independent activity measurements.

  • b Samples used for RNA isolation and Cy3 or Cy5 labeling and subsequent hybridization to microarray. OD600S of these cultures were almost identical (OD600 = 1.2). Fold induction results from three replicate experiments agreed within 10%. exp, experimental.