Fig. 3.

Spores containing sqhC are more resistant to hydrogen peroxide. Wild-type colorimetrically marked cells (amyE::PSpac-lacZ) (TB38) and cells lacking sqhC (ΔsqhC ΔsodF::tet) (TB10) were mixed in 10:90 initial ratio in liquid sporulation medium. Purified spores were treated with heat and hydrogen peroxide. A small aliquot of spores was used to determine the ratio of wild-type and mutant cells in the population and the rest was used to inoculate the next cycle of the experiment for eight consecutive cycles. The treatment included the incubation of spores in the presence of 1% H₂O₂ (open squares) and the absence of H₂O₂ (filled triangles). The same experiment was repeated with a mixture of TB38 cells and cells mutant for sqhC and sodF that contained a functional copy of sqhC (ΔsqhC ΔsodF::tet, thrC::PsqhC-sqhC) (TB71, filled squares). The observed trend was not influenced by the presence of the gene encoding for the colorimetric marker lacZ (Fig. S5).