Polyphasic taxonomy of Aspergillus section Candidi based on molecular, morphological and physiological data.

Area of Science:

• Mycology
• Fungal Taxonomy
• Molecular Biology

Background:

• Aspergillus section Candidi was historically defined by a single species, A. candidus.
• Recent studies suggested the inclusion of additional species within this section.

Purpose of the Study:

• To clarify the taxonomic status of species within Aspergillus section Candidi.
• To delineate distinct species using a polyphasic approach.

Main Methods:

• Polyphasic taxonomic study integrating molecular (beta-tubulin, calmodulin, ITS sequencing) and phenotypic data.
• Morphological and physiological characterization of fungal isolates.
• Analysis of extrolite profiles using chemical methods.

Main Results:

• The revised Aspergillus section Candidi comprises four species: A. candidus, A. campestris, A. taichungensis, and A. tritici.
• Distinct morphological traits, including colony growth, conidial heads, and conidia shape, support species delineation.
• Unique extrolite profiles, such as terphenyllins, candidusins, chlorflavonins, and xanthoascins, aid in species identification.
• Aspergillus tritici is confirmed as a distinct species, not a synonym of A. candidus, and is geographically widespread.

Conclusions:

• The polyphasic approach successfully resolved the taxonomy of Aspergillus section Candidi.
• Each of the four identified species exhibits unique extrolite production, serving as chemotaxonomic markers.
• Re-evaluation of pathogenicity suggests A. tritici or A. flavus mutants, not A. candidus, are potential human pathogens.