Fig. 6. Sensing peptidoglycan regulates the transcription from the promoters of NRPs and PKS biosynthetic clusters.

a Analysis of the luciferase activity in a WT B. subtilis strain harboring P_pksC-lux (bacillaene) reporter. Luminescence was monitored in B4 medium (No Treatment), and B4 medium supplemented with 15% v/v of the conditioned medium (CM), or an equivalent amount of the conditioned medium fractionated to generate LF (>3 kDa) and peptidoglycan PG (100 ng/µl) from the indicated species. Graphs represent mean ± SD from three independent experiments (n = 9). Statistical analysis was performed using two-way ANOVA followed by Dunnett’s multiple comparison test. P < 0.05 was considered statistically significant. b Representative peaks from liquid chromatography-mass spectrometry analysis of bacillaene from the WT B. subtilis grown in untreated B4 medium (control) or in a B4 medium treated with purified PG (100 ng/µl) of indicated species at 24 h. c Liquid chromatography-mass spectrometry analysis of surfactin isoform 1 and bacillaene from WT B. subtilis grown in untreated B4 medium (control), and B4 medium supplemented with PG (100 ng/µl) from the indicated species. Supernatant was extracted from the samples at 16 h and 24 h using HCl treatment. Graphs represent mean ± SEM from four biological repeats (n = 4). Statistical analysis was performed using Brown–Forsthye and Welch’s ANOVA with Dunnett’s T3 multiple comparisons test. P < 0.05 was considered statistically significant. P values comparing the effect on each fluorescent reporter when competing against different Bacilli in panel a are shown in the Supplementary Data 1. Source data are provided as a Source Data file.