FIG 9.

The luxO* strain JHK061 shows a defect when competed 1:1 against the wild-type ES114 derivative AKD200 during colonization of E. scolopes. Newly hatched squid (n = 29) were exposed to a mixed inoculum of JHK061 [luxO*(T335I)] and AKD200 (∼2,000 CFU) in filter-sterilized Instant Ocean for 12 h with subsequent water change at 24 h. After 48 h, squid were homogenized, dilution plated on LBS agar, and patched to determine Cam resistance. The log relative competitive index (RCI) was calculated as the log of the ratio of JHK061 to AKD200 in the host homogenate to the ratio of the two strains in the inoculum. The solid line represents an equal ability to colonize the host; the dashed line represents the mean log RCI of −0.75. Data from a single representative experiment of three independent experiments is shown. Statistical significance was determined using a one-sample Student's t test where the null hypothesis is a mean log RCI of 0. Each diamond represents the log RCI in one hatchling.