FIG 2.

Phenotypic in vitro characterization of the mutant strains. (A) rbdA and dscE are required for hypoxia adaptation in A. fumigatus. ΔrbdA, ΔdscE, and control AkuB^KU80 and ΔsrbA strains were grown on YAG plates for 48 h at 37°C under normoxic (upper panel, 21% O₂) and hypoxic (lower panel, <1% O₂) conditions. (B) The ΔrbdA and ΔsrbA mutant strains are hypersensitive to CoCl₂. The droplet dilution assay was used to evaluate strain sensitivity toward hypoxia. The strains were grown on YAG rich plates for 48 h at 37°C under increasing concentrations of CoCl₂, as indicated above the images. An increase in sensitivity toward hypoxia was observed for the ΔrbdA and ΔsrbA mutant strains, whereas for the reconstituted strain, rbdA-KI, this sensitivity was restored and is similar to that of the AkuB^KU80 background strain. (C) The ΔrbdA and ΔsrbA mutant strains do not form a biofilm rim. Strains were grown in shaking liquid culture (YAG) for 48 h at 37°C. AkuB^KU80 control and reconstituted rbdA-KI strains form a biofilm rim (indicated by white arrows), whereas the ΔrbdA and ΔsrbA mutant strains do not. The ΔstuA mutant strain, which does not form a biofilm, was used as a negative control.