Fig 2.

Comparison of sod expression in P. gingivalis 33277 and its mutant strains. The oxyR mutant, the cdhR mutant, the hmuY mutant, and the parent strain 33277 were grown with or without hemin for three passages. Expression of sod was measured using real-time RT-PCR. Each bar represents the increase of sod expression in P. gingivalis grown without hemin compared to expression in strains grown with hemin, which was normalized to the change in glk expression. Error bars represent standard deviations. Asterisks indicate a statistically significant difference in sod expression levels in P. gingivalis grown with and without hemin (t test; P < 0.05).