FIG 2.

OMV-associated CAI-1 activates QS cascade in V. harveyi reporter strain at population level. (A) Schematic depiction of OMV harvesting process by fractionating of the V. harveyi supernatant. (B) Each fraction from MR17 cells (ΔluxM ΔluxS) was tested for QS activation in the reporter strains NL20 (ratio of OMVs to reporter strain culture, 1:6.7) by measuring luminescence as the readout. The reporter strain NL20 senses only CAI-1 and strain MR17 synthesizes only CAI-1. As a control, the OMV-containing 0.45-μm filtrate of the non-CAI-1 producing strain MR16 (ΔcqsA ΔluxM) was tested for QS activation in the reporter strains NL20. Error bars represent the standard deviations of data from three different experiments. RLU, relative light units, expressed in counts per second per milliliter per OD₆₀₀ unit. SN, culture supernatant of MR17; OMVs (0.45μm filtrate), filtrate of SN of MR17 cells through 0.45-μm filter; OMVs (0.22μm filtrate), filtrate of SN of MR17 cells through an additional 0.22-μm filter; LM, cell-free culture medium as control; OMVs CAI-1⁻, filtrate of SN of MR16 cells through 0.45-μm filter. Time courses of the growth and luminescence production of the reporter strain NL20 are shown in Fig. S1.