Abstract

Hyphomycetous fungi originating from South Africa were morphologically characterised and ascribed to the genera Acremonium, Aspergillus and Penicillium, respectively. The primary means of spore dispersal employed by these isolates was investigated by quantifying colony forming units released into the air and into an aqueous solution. Measurement of spore liberation during humid aeration, revealed significant (P < 0.0001) differences among the hyphomycetous taxa investigated. Isolates of the genus Penicillium were more successful in releasing their spores than the Aspergilli and the Acremonium isolate. Spore liberation during desiccated aeration also showed a significant (P < 0.0001) difference between the respective isolates. Overall, isolates belonging to the genus Penicillium released more viable spores than Aspergillus spp., which in turn released more spores than Acremonium. In support of the theory that splashing rain may dislodge and disperse microfungal propagules, washing respective cultures with physiological salt solution resulted in an immediate massive spore release. However, the taxa investigated did not differ. These differences in airborne spore release that were observed between the hyphomycetous genera may be a result of different strategies to disperse their spores in nature. This phenomenon should be investigated further in future and the challenge now is to find correlations between the conidiophore morphology of each fungus and characteristics of their niche.

Key words: Acremonium, Aspergillus, Hyphomycetes, Penicillium, spore dissemination.