FIG. 9.

Autoradiograph of Northern hybridization of total RNA. A and B) B. fragilis 638R and isogenic fur mutant were grown to mid-log phase in SDM containing 100 μM FeSO₄ for iron-replete conditions (+Fe) and SDM containing 50 μM 2,2′-bipyridyl and 100 μM desferrioxamine to impose iron-limiting conditions (−Fe). Protoporphyrin IX (PpIX) was added to the medium as a source of tetrapyrrole macrocycle. The probe was an internal fragment from hlyA (panel A) or hlyB (panel B). The positions of the hlyA and hlyB mRNA components are indicated. The asterisk depicts the 16S compression region on the filter membrane. (C) B. fragilis 638R was grown in SDM supplemented with 5 μg/ml hemin and exposed to different oxidative stress conditions. The probe was an internal fragment of hlyA.