Flow cytometry monitoring the expression of the reporter PtapA-yfp (YFP fluorescence on the y-axis) and Phag-cfp (CFP fluorescence on the x-axis) from cells grown on MSgg medium. The number of cells is represented by isolines. The top left panel shows the control of background fluorescence for both CFP and YFP in a strain harbouring no fluorescent protein genes (DL1). Top right panel: the strain harbouring PtapA-yfp (DL382). The subpopulation expressing fluorescence above background is framed in yellow. Centre left panel: the strain harbouring Phag-cfp (DL1056) showed a subpopulation of cells highly expressing the reporter framed in blue. Centre right panel: the strain harbouring both reporters, PtapA-yfp and Phag-cfp (DL1079). Bottom left panel: the ΔftsH mutant strain harbouring both reporters, PtapA-yfp and Phag-cfp (DL1521). Bottom right panel: the ΔftsH mutant strain harbouring both reporters, PtapA-yfp and Phag-cfp, complemented with the gene ftsH controlled by an IPTG-inducible promoter (DL1523, induction with 1 mM IPTG).