Fig. 4. Assessment of pigmentation and growth/viability phenotypes of P. gingivalis 381 and ΔrelΔrshB containing pC-COW (empty vector controls) and complemented ΔrelΔrshB (pC-rel or pC-rshB).
a When grown overnight to the stationary phase in TSBHK, the ppGpp0 mutant (ΔrelΔrshB) lacks pigmentation, indicative of a defect in heme binding. When the deletion mutant was complemented by any one of the ppGpp synthesis genes from a plasmid (pC-rel or pC-rshB), the pigmentation was partially restored. b P. gingivalis 381/pC-COW (circles), ΔrelΔrshB/pC-COW (crosses), ΔrelΔrshB/pC-rel (squares), and ΔrelΔrshB/pC-rshB (triangles) were grown in CDMTHK media in the presence of chloramphenicol. Points indicate the mean values, and error bars indicate standard deviations from three replications.