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Updating the 97% identity threshold for 16S ribosomal RNA OTUs

Open access
Edgar, Robert C·2018·Bioinformatics

Abstract

Motivation: The 16S ribosomal RNA (rRNA) gene is widely used to survey microbial communities. Sequences are often clustered into Operational Taxonomic Units (OTUs) as proxies for species. The canonical clustering threshold is 97% identity, which was proposed in 1994 when few 16S rRNA sequences were available, motivating a reassessment on current data. Results: Using a large set of high-quality 16S rRNA sequences from finished genomes, I assessed the correspondence of OTUs to species for five representative clustering algorithms using four accuracy metrics. All algorithms had comparable accuracy when tuned to a given metric. Optimal identity thresholds were ∼99% for full-length sequences and ∼100% for the V4 hypervariable region. Availability and implementation: Reference sequences and source code are provided in the Supplementary Material. Supplementary information: Supplementary data are available at Bioinformatics online.

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Metadata

Authors
Edgar, R. C.
Venue
Bioinformatics
Published
2018-02-28
Volume
34
Issue
14
Pages
2371-2375
ISSN
  • 1367-4803 (ISSN-L)
  • 1367-4811
OpenAlex
W2757805629
Cited by
723
References
6
FWCI
24.25
Type
journal article
Language
en
Open access
bronze

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CoChat. (2026). Citation check: Updating the 97% identity threshold for 16S ribosomal RNA OTUs. https://app.cochat.ai/papers/10.1093/bioinformatics/bty113
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Edgar, R. C. (2018). Updating the 97% identity threshold for 16S ribosomal RNA OTUs. Bioinformatics. https://doi.org/10.1093/bioinformatics/bty113

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