Figure 1.
Aspergillus fumigatus ascospores.
A) SEM image of an ascospore produced by mating between two compatible strains. Courtesy of Bryan Hansen. B) TEM image of an ascospore cross-section showing an unusually thick wall (white bar) composed of an electron-dense inner wall covered by a thick outer wall. Courtesy of Mones Abu-Asab. C) DIC image of germinating ascospores (white arrows) and dead conidia (black arrow) after 30 min incubation at 70°C.
Figure 2.
Dispersibility of A. fumigatus conidia.
A) A cloud of aerosol released in the air after turning of a compost pile located in Maryland, USA. B) A malt extract agar plate exposed to the air for a minute at the site and incubated for a few days at 37°C grew predominantly A. fumigatus colonies (both pictures were taken by the late Dr. Chester Emmons). C) Eight small sterile agar plates of Aspergillus minimal medium were placed around a seven-day-old culture of A. fumigatus strain B-5233 (center) in a class 2 biosafety cabinet. In the absence of air flow the lids of all the plates were removed for 24 h. The small plates were then incubated for three days at 37°C. D) The same procedure as in C except that the small plates were exposed to the culture of a ten-day-old A. nidulans strain RYC13B (center). A. fumigatus conidia dispersed to the surrounding small agar plates while none was evident for the A. nidulans strain.