Abstract
In an attempt to confirm the heat resistance of conidiospores of A. fumigatus, quantitative counts were made of their percentage of germination after hating by agar disc technique.
It was clearly shown that the germination of untreated conidia of A. fumigatus was quite successful under the simple experimental conditions; their percentage of germination amounted to 98%. Only matured conidia of A. fumigatus were of thermal resistance and those of most strains of the fungus survied 2h at 60°C, but the germination percentage decreased gradually with increasing time of heating, obtaining 4-6% germination after heating for 2h. The conidia of five other Aspergillus species, except for A. fumigatus, lost their ability to germinate after exposure to 60°C within 5min. It was suggested that there seemed to be a recovery mechanism from the damage of certain conidiai constituents which had been inactivated by heat, since the germination percentage might increase with increasing time of recovery incubation.
