Fig. 1

The spore staining results of B. cereus 0–9 and its ΔspoVG mutant. Tested strains were cultured in MG medium at 30 °C and 220 rpm for 6 h, 24 h and 48 h, respectively. When B. cereus 0–9 was stained with malachite green, matured spores will be stained blue, and the cells will be stained red. The cortical defective spores, unable to trap malachite green, will also be stained red by safranin. Thus, for ΔspoVG without mature spores, no blue spots were observed after staining under the light microscope