<i>spo0M</i> null mutant shows morphological alterations compared to the wild type strain.

<p>We generated a <i>spo0M</i> null mutant by allelic replacement of a pΔ0M construct (<b>A</b>) (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0172737#pone.0172737.s001" target="_blank">S1 File</a>) in the <i>spo0M</i> gene. KnR, kanamycin resistance cassette. <b>B</b>. Spore quantification for the wild type and mutant strains. The wild type and mutant strains were cultured in Spizizen sporulation medium for 40 h. The total number of spores in each sample was quantified manually using a bright field microscope. The Δ0M strain generated 20–25% fewer spores than the wild type strain. The sporulation efficiency of the SCK6 parental strain was similar to that of the wild type Bs1A1 strain. <b>C</b>. Analysis of spore resistance in wild type and mutant strains. Spores of wild type and mutant strains were generated in 2XSG medium and subjected to wet heat and chemical treatment as mentioned in Materials and methods. Mutant spores are less resistant to both treatments, compared to those generated by the wild type strain. Data was analyzed through an ANOVA test, with a <i>p</i> value of 0.001, blue bar corresponds to the mean value and red bar represents the standard deviation. <b>D</b>. We analyzed the phenotype of the mutant strain using light microscopy and observed that the mutant adopted an elongated appearance compared with the wild type strain. Cell length was measured using the Fiji—ImageJ software [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0172737#pone.0172737.ref031" target="_blank">31</a>].