FIG. 4.

Effect of heme addition on PsADH1 and PsCYC1 expression in anaerobic cells. Cells were grown aerobically on xylose until they reached an OD₆₀₀ of 1.0, collected by centrifugation, and shifted to oxygen-limited conditions by suspension in the same medium. After the cells had been shifted to oxygen limitation, heme (50 μg/ml) or protoporphyrin IX (p.p. IX [50 μg/ml]) was added as indicated, and growth was continued under oxygen-limited conditions for 4 h. The RNA blot was hybridized with PsADH1- or PsCYC1-specific oligonucleotides as probes.