37 research outputs found
Polyphasic taxonomy of Aspergillus section Candidi based on molecular, morphological and physiological data
Aspergillus section Candidi historically included a
single white-spored species, A. candidus. Later studies clarified
that other species may also belong to this section. In this study, we examined
isolates of species tentatively assigned to section Candidi using a
polyphasic approach. The characters examined include sequence analysis of
partial β-tubulin, calmodulin and ITS sequences of the isolates,
morphological and physiological tests, and examination of the extrolite
profiles. Our data indicate that the revised section Candidi includes
4 species: A. candidus, A. campestris, A. taichungensis and A.
tritici. This is strongly supported by all the morphological
characteristics that are characteristic of section Candidi: slow
growing colonies with globose conidial heads having white to yellowish
conidia, conidiophores smooth, small conidiophores common, metulae present and
covering the entire vesicle, some large Aspergillus heads with large
metulae, presence of diminutive heads in all species, conidia smooth or nearly
so with a subglobose to ovoid shape, and the presence of sclerotia in three
species (A. candidus, A. taichungensis and A. tritici).
Aspergillus tritici has been suggested to be the synonym of A.
candidus previously, however, sequence data indicate that this is a valid
species and includes isolates came from soil, wheat grain, flour and drums
from India, Ghana, Sweden, The Netherlands and Hungary, making it a relatively
widespread species. All species produce terphenyllins and candidusins and
three species (A. candidus, A. campestris and A.
tritici) produce chlorflavonins. Xanthoascins have only been found in
A. candidus. Each of the species in section Candidi produce
several other species specific extrolites, and none of these have been found
in any other Aspergillus species. A. candidus has often been
listed as a human pathogenic species, but this is unlikely as this species
cannot grow at 37 °C. The pathogenic species may be A. tritici or
white mutants of Aspergillus flavus