A survey of xerophilic Aspergillus from indoor environment, including descriptions of two new section Aspergillus species producing eurotium-like sexual states

Abstract

Xerophilic fungi grow at low water activity or low equilibrium relative humidity and are an important part of the indoor fungal community, of which Aspergillus is one of the dominant genera. A survey of xerophilic fungi isolated from Canadian and Hawaiian house dust resulted in the isolation of 1039 strains; 296 strains belong to Aspergillus and represented 37 species. Reference sequences were generated for all species and deposited in GenBank. Aspergillus sect. Aspergillus (formerly called Eurotium) was one of the most predominant groups from house dust with nine species identified. Additional cultures deposited as Eurotium were received from the Canadian Collection of Fungal Cultures and were also re-identified during this study. Among all strains, two species were found to be new and are introduced here as A. mallochii and A. megasporus. Phylogenetic comparisons with other species of section Aspergillus were made using sequences of ITS, β-tubulin, calmodulin and RNA polymerase II second largest subunit. Morphological observations were made from cultures grown under standardized conditions. Aspergillus mallochii does not grow at 37 °C and produces roughened ascospores with incomplete equatorial furrows. Aspergillus megasporus produces large conidia (up to 12 µm diam) and roughened ascospores with equatorial furrows. Echinulin, quinolactacin A1 & A2, preechinulin and neoechinulin A & B were detected as major extrolites of A. megasporus, while neoechinulin A & B and isoechinulin A, B & C were the major extrolites from A. mallochii.