Effect of <i>luxI</i> and 3OC6 on derepression of the <i>lux</i> operon in an <i>arcA</i> mutant.

<p>Luminescence or <i>lux</i> reporter expression was measured in strains ES114 (WT), AMJ2 (Δ<i>arcA</i>), VCW2G7 (<i>luxI</i> mutant), or ANS7 (Δ<i>arcA luxI</i>). (A) Peak specific luminescence (luminescence per OD₅₉₅) of strains grown in SWTO in aerobic shake flasks. Error bars indicate standard deviation (n = 3). (B) Plasmid based P<i>_luxI</i>-<i>lacZ</i> transcriptional reporter assays. Strains containing pJLB171 or the promoterless vector pAKD702 were grown in duplicate aerobic shake flasks in SWTO medium. Cells were harvested at peak luminescence for ß–galactosidase assays. Error bars indicate standard deviation (n = 2). Asterisk indicates p-value of <0.05 with a Student’s t-test comparing the <i>arcA</i> mutant to its respective parent strain. (C) Peak specific luminescence values for aerobic cultures grown in SWTO medium with 50 nM 3OC6 added where indicated. Error bars (some too small to see) indicate standard deviation (n = 2). Each panel is representative of at least three independent experiments.