Fig. 3

The characterization of the sporulation-deficient mutants and wild-type strain. The red arrow gave directions of every typical morphology (×100). a The cell morphology was observed by crystal violet (a1–a3) staining assay and Schaeffer-Fulton staining assay (a4): a1, “rod” like cellular morphology of the strains under the optical microscopy (OM); a2, cellular morphology with cell lysis of the spo0A mutant under OM; a3, an abortively disporic cell with two asymmetric septa under OM; a4, mature endospores in the parent strain under OM. b The cell morphology was observed under scanning electron microscopy (SEM) (×5000): b1, “rod” like cellular morphology of the strains under SEM; b2, an abortively disporic cell with two asymmetric septa under SEM; b3, mature spores in the parent strain under SEM. c The colonial morphology of the mutants and control strain in LB plate. d The cell growth curve of different strains