A comprehensive, automatically updated fungal ITS sequence dataset for reference-based chimera control in environmental sequencing efforts
Artikel i vetenskaplig tidskrift, 2015

The nuclear ribosomal internal transcribed spacer (ITS) region is the most commonly chosen genetic marker for the molecular identification of fungi in environmental sequencing and molecular ecology studies. Several analytical issues complicate such efforts, one of which is the formation of chimeric—artificially joined—DNA sequences during PCR amplification or sequence assembly. Several software tools are currently available for chimera detection, but rely to various degrees on the presence of a chimera-free reference dataset for optimal performance. However, no such dataset is available for use with the fungal ITS region. This study introduces a comprehensive, automatically updated reference dataset for fungal ITS sequences based on the UNITE database for the molecular identification of fungi. This dataset supports chimera detection throughout the fungal kingdom and for full-length ITS sequences as well as partial (ITS1 or ITS2 only) datasets. The performance of the dataset on a large set of artificial chimeras was above 99.5%, and we subsequently used the dataset to remove nearly 1,000 compromised fungal ITS sequences from public circulation. The dataset is available at http://unite.ut.ee/repository.php and is subject to web-based third-party curation.

molecular ecology

reference dataset

chimera detection


PCR artifacts


R. Henrik Nilsson

Göteborgs universitet

Leho Tedersoo

University of Tartu

Martin Ryberg

Uppsala Universitet

Erik Kristiansson

Chalmers, Matematiska vetenskaper, matematisk statistik

Göteborgs universitet

Martin Hartmann

Institute for Sustainability Sciences

Eidgenossische Forschungsanstalt fur Wald, Schnee Und Landschaft Eth-Bereichs

Martin Unterseher

Ernst-Moritz-Arndt-Universitat Greifswald

Teresita M. Porter

McMaster University

Johan Bengtsson-Palme

Göteborgs universitet

Donald M. Walker

University of Findlay

Filipe de Sousa

Göteborgs universitet

Hannes Andres Gamper

ETH Zurich

Ellen Larsson

Göteborgs universitet

Karl-Henrik Larsson

Natural History Museum

Urmas Kõljalg

University of Tartu

Robert C. Edgar

Kessy Abarenkov

University of Tartu

Microbes and Environments

1342-6311 (ISSN) 1347-4405 (eISSN)

Vol. 30 145-150


Biologisk systematik





Bioinformatik (beräkningsbiologi)

Mikrobiologi inom det medicinska området

Bioinformatik och systembiologi