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United States Department of Agriculture

Agricultural Research Service

Research Project: MANAGEMENT AND GENETIC CHARACTERIZATION OF AGRICULTURAL AND BIOTECHNOLOGICAL MICROBIAL RESOURCES Title: Taxonomic revision of Eurotium and transfer of species to Aspergillus

Authors
item Hubka, Vit -
item Kolarik, Miroslav -
item Kubatova, Alena -
item Peterson, Stephen

Submitted to: Mycologia
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 26, 2012
Publication Date: July 1, 2013
Citation: Hubka, V., Kolarik, M., Kubatova, A., Peterson, S.W. 2013. Taxonomic revision of Eurotium and transfer of species to Aspergillus. Mycologia. 105(4):912-937.

Interpretive Summary: The molds within Aspergillus section Aspergillus are tolerant of very dry conditions, and significant economic impact is derived from their deterioration of stored seeds, cereals, cured meats, and many other products preserved by drying. Currently, the different species within this group can’t be identified and differentiated because of common spontaneous mutations that result in atypical appearance. We performed DNA sequence analyses of a diverse collection of these molds in order to provide an appropriate description of these species and a means for their identification. Using these data, we described 17 dry-tolerant species and found three genetic regions that can be used to identify individuals even when their appearance is abnormal. This information will be of value to food technologists, food processors, mycologists, and other scientists that rely on the ARS Culture Collection to provide well-characterized germplasm for scientific investigation.

Technical Abstract: Section Aspergillus contains economically important, xerophilic species widely distributed in nature and the human environment that are known for their ability to grow on substrates with low water activity. The high level of phenoplasticity and frequent occurrence of mutants with atypical morphology contributed to excessive description of new species within section Aspergillus. The taxa were subjected to revision using the sequence data from four loci, PCR-fingerprinting method, micro- and macromorphology and physiology. Using polyphasic approach, we reduced the number of taxa to 17 species including a newly proposed species Aspergillus pragensis. This new species is represented by two isolates originating from human nails with onychomycotic changes and one isolate from cave sediment. In addition, we supplemented the original description of A. proliferans by description of its teleomorph. A. proliferans seems to be a relatively common species which was often confused with A. glaucus. We also provided scanning electron microscopy (SEM) photos of species whose ascospores have not been documented. In addition to molecular methods, ascospore size, ornamentation and ability to grow at combination of temperature and osmotic gradient seems to be the most reproducible feature for taxonomy. A dichotomous key to the species is provided predominantly using these characters. Conidial size and ornamentation has a limited taxonomical value and the anamorph does not develop or is extremely rare in several taxa grown under standard conditions. We describe suitable condition for development of anamorphic features to aid species identification. We transferred the Eurotium species to Aspergillus and propose one name for each species in accordance with recent nomenclature rule changes.

Last Modified: 11/24/2014
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