A collection of 94 Aspergillus fumigatus sensu lato isolates was cultured from air samples taken at four outdoor locations during 2005 . A polyphasic approach was employed for the identification of the isolates, using morphological, physiological and molecular data. Phenotypic characters were examined using established protocols  and included the macro- and micromorphology of the isolates, their maximal and minimal growth temperatures and their 25 Â°C/45 Â°C growth ratio. Results confirmed that all 94 isolates were A. fumigatus sensu stricto. Genotypic variation within the population was analysed by RAPD-PCR which revealed that the isolates are closely related but not identical. The distribution of the two complementary mating-type genotypes of the fungus (termed MAT1-1 and MAT1-2) was then determined using a multiplex mating-type PCR assay . The population consisted of equal proportions of the MAT1-1 and MAT1-2 genotypes (49.4% MAT1-1, 50.6% MAT1-2), with no geographical clustering of mating-types evident. A representative sub-sample of 12 isolates from the population was chosen for further examination by multi-locus sequence typing of partial íŸ-tubulin and carboxypeptidase gene sequences. Phylogenetic analysis clearly grouped the 12 representative isolates with known Aspergillus fumigatus sensu stricto isolates. The results show that A. fumigatus isolates of complementary mating-type can be readily found in close proximity in nature, consistent with a sexually reproducing species.
Full conference title:
9th EUROPEAN CONFERENCE ON FUNGAL GENETICS
- ECFG 9th (2008)