Fig. 7: Distribution of sporulating cells in biofilm colony is modulated by σB expression.
a Spore density at the top of biofilm colonies in WT and 2 × rsbQP strains. The graph represents a ratio of amount of cells identified as spores (by expression of the PsspB-YFP fluorescent marker) to the combined amount of all cells expressing PsigA-RFP and spores (see the section “Methods” for details of quantification). For WT, data is replotted from Fig. 5a, n = 11 from four experiments, for 2 × rsbQP data, n = 12 from four experiments. Error bars represent SEM. b Doubling of rsbQP gene copy number increases and sharpens σB expression gradient in biofilm colonies. The graph represents a ratio of PsigB-YFP to PsigA-RFP expression in WT (black) and 2 × rsbQP (brown) backgrounds in biofilm colonies as measured from the distance from the colony top. (WT data n = 13 from three experiments, 2 × rsbQP n = 7 from 1 experiment). Error bars show the SEM. Scale bars are 25 μm. c, d representative images of the spore pattern in a WT and 2 × rsbQP biofilm respectively, PsigA-RFP in red and PsspB-YFP in cyan. All samples are from the central part of the biofilm and collected at 48 h after inoculation. Note that in c, between the biofilm and agar, is a layer of spores. This is typical of WT biofilms and is not reflected in the spore gradient a since there are no cells to compute a ratio. The full context for c and d is shown in Supplementary Fig. 12. Source data are provided as a Source Data file.
