TABLE 3.

Effect of exogenous AHL on phenazine production in gacA and gacS mutants

Prepn	Phenazine absorbancea
30-84I (AHL− control)	0.035 ± 0.002 A
30-84I + AHL	0.563 ± 0.040 B
30-84.gacA	0.040 ± 0.007 A
30-84.gacA + AHL	0.040 ± 0.005 A
30-84W	0.034 ± 0.003 A
30-84W + AHL	0.038 ± 0.004 A
30-84.A2	0.042 ± 0.002 A
30-84.A2 + AHL	0.048 ± 0.007 A

^aAbsorbance at 367 nm of phenazine extracted from culture supernatants and resuspended in 0.1 N NaOH. Exogenous AHL was extracted from 30-84Ice and resuspended in PPMD medium. PPMD medium containing AHL was filter sterilized and inoculated with each test strain. Strain 30-84I was included as the AHL-negative control. The values are means ± standard errors based on three replicates per treatment. Means followed by the same letter are not significantly different.