Fig 5.
Regulatory determinants of luminescence induction in response to low iron. V. fischeri cultures were grown in aerobic shake flasks in SWTO medium supplemented with 43 μM FeSO4 either without or with 20 mM citrate. Error bars indicate standard deviations (n = 3). Asterisks indicate a significant effect of citrate addition on luminescence of the strain (P < 0.03), as determined by using Student's t test, while the dagger indicates variable statistical significance (P value ranged from 0.0001 to 0.73 in 11 experiments [see the text for details]). In the representative experiment shown, citrate addition to Δfur mutant cultures resulted in a small (16%) but statistically significant (P < 0.05) increase in peak luminescence. Data shown were collected from the same experiment and are representative of at least three independent experiments for each strain.