FIG. 2.

Analysis of cell-free culture fluids for CAI-1 activity. (A) Cell-free culture fluids were prepared from the strains shown and added at 30% (vol/vol) to V. cholerae MM920. Light production by MM920 was measured. Strain names are as follows (left to right): KSK1052, MM893, BB120, JAF633, KM387, KM413, JMH603, JMH598, DH5α, MM1467. (B) CAI-1 production over the growth curve is shown for WT V. harveyi strain BB120. Samples were collected every 2 h, the OD₆₀₀s were measured, and cell-free culture fluids were prepared and assayed for CAI-1 activity using MM920. CAI-1 activity is reported as the fold induction of light production in MM920.