FIG. 6.

Competition during mixed infection between V. fischeri EW1 (Δphr) and JRM100. JRM100 is a derivative of ES114 marked with an intergenic mini-Tn7-ermR insertion that does not affect competitiveness (26). Juvenile squid were exposed to an ∼1:1 mixture of the strains at a total concentration of 2,500 CFU ml⁻¹ for 14 h, and the RCI of EW1, defined as the ratio of EW1 to JRM100 in the squid divided by the ratio of these strains in the inoculum, was determined for each coinfected animal 48 h after inoculation. The RCI is plotted as a circle. A dotted line marks the RCI of 1, where the strain ratio in the squid matches that in the inoculum and there is no difference in strain competitiveness.