Fig. 2.

Genotoxic stress induces MV formation through activation of the holin–endolysin system. a Fold-change of MV production of MMC-treated cells relative to non-treated cells. n = 3; mean ± s.d. **P < 0.01 (unpaired t-test with Welch’s correction). b Expression of the PBSX holin–endolysin gene cluster is induced by MMC. A transcriptional fusion of the P_L promoter, which drives transcription of the PBSX late operon (including the holin–endolysin genes), to zsGreen was quantified by flow cytometry. Green curve shows activity of the P_L promoter; black curve shows activity of the vector control. c Promoter (P_L) activities of the PBSX holin–endolysin gene cluster under MMC non-inducing and inducing conditions. The image shows FM4-64 (red) merged with ZsGreen (green). Scale bar, 5 μm. Phase contrast images along with the images of control experiments are shown in Supplementary Fig. 2a. d Fold-change of MV production by the expression of holin–endolysin genes relative to the control strain 168 (P_xylA). ***P < 0.001 (unpaired t-test with Welch’s correction). e Live cell imaging of MV formation in B. subtilis 168 (P_xylA -xhlAB-xlyA) cells. Arrows indicate MVs. Cells were incubated on LB agarose pads containing 0.1% xylose, FM4-64 (red) and SYTOX green (green). Scale bar, 5 μm