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. 2013 Dec 11;8(12):e82514. doi: 10.1371/journal.pone.0082514

Figure 1. Validation of the specificity and sensitivity of the QS reporter system in Brucella melitensis 16M.

Figure 1

(a) Immunofluorescence of the B. melitensis control strain incubated 4 hours with C12-HSL (1 µM) and labelled with monoclonal A76-12G12 anti-LPS antibody (red). No GFP(ASV) signal is detected. (from b to e) Observation of GFP(ASV) production by the B. melitensis reporter strain after a 4h incubation with various concentrations of synthetic C12-HSL; (b) 1nM, (c) 10nM, (d) 100nM, (e) 1 µM; scale bar 5 µm. (f) Measurement of GFP(ASV) fluorescence intensity by flow cytometry (5×104 events acquired) in the B. melitensis QS reporter strain fixed after a 4h-incubation with 0.1nM or 1nM of C12-HSL or 3-oxo-C12HSL. The B. melitensis control strain was used as a negative control (black dotted line). The results are representative of at least two independent experiments.