Fig 3. Effect of a codY null mutation on tcdA and tcdB transcription in strain UK1.

Cultures of strains UK1, LB-CD16 (codY::intron::erm) and ND-CD10 (codY::intron::erm codY⁺) were grown in CDMM medium and samples were removed at 8 hrs (late exponential growth phase) and 24 hrs (stationary phase). RNA was extracted and assayed for tcdA and tcdB expression by qRT-PCR (see Materials and Methods). Results for the toxin genes were normalized to those obtained for the rpoA gene.