HPLC-MS/MS ion chromatograms of AHLs produced by
LFI1238 and QS mutants.
(A) The wild type LFI1238 produces eight AHLs those being the C4-HSL, 3-oxo-C4-HSL, C6-HSL, 3-oxo-C6-HSL, C8-HSL, 3-oxo-C8-HSL, and 3-oxo-C10-HSL and 3-OH-C10-HSL. (B) The ΔainS mutant lacks 3-OH-C10-HSL production, and the chromatogram shows the seven remaining AHLs. (C) The luxIˉ mutant produces only 3-OH-C10-HSL and (D) no AHLs were detected in the supernatants harvested from the double mutant ΔainS/ luxIˉ. The peaks of the different AHLs were scaled so that the different AHLs could be shown in the same chromatogram. The scaling factors were as follows: 1.6 × 103 for 3-oxo-C4-HSL, 6.0 × 103 for C4-HSL, 9.0 × 105 for 3-oxo-C6-HSL, 2.7 × 105 for C6-HSL, 5.4 × 104 for 3-oxo-C8-HSL, 1.5 × 104 for C8-HSL, 1.9 × 104 for 3-OH-C10-HSL and 1.0 x 104 for 3-oxo-C10-HSL. The same scaling was used for all four chromatograms (A, B, C and D). The numbers above the peaks are mass-to-charge ratios (m/z).