Fig. 2

Activity of spa promoters in wild type B. subtilis W168 and single mutants. spa promoters fused to the luciferase cassette (luxABCDE) were integrated into the chromosome of B. subtilis W168 (A) and the mutants ΔabrB (B), ΔsigH (C) and Δspo0A (D), respectively. The activity of spa promoters in different genetic backgrounds was evaluated using a microplate reader and represented by the luciferase activity (RLU/OD₆₀₀), which is shown as the raw luminescence output (relative luminescence units, RLU) normalized by the cell density (OD₆₀₀). The dynamics of spa promoter activity during growth are shown in Additional file 3: Fig. S2. The respective peak activity around the transition point into stationary phase was plotted here to represent the corresponding promoter activity. The strain containing a promoterless lux fusion was used as control as shown in A. Error bars represent the standard deviations from two biological replicates with each measurement carried out in triplicates. ns not significant, *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001