Cited by 3,493Genomics and Phylogenetic StudiesMicrobial Community Ecology and PhysiologyEnvironmental DNA in Biodiversity Studies

Simple statistical identification and removal of contaminant sequences in marker-gene and metagenomics data

Open access
Davis, Nicole M., Proctor, Diana M., Holmes, Susan P., Relman, David A., Callahan, Benjamin J.·2018·Microbiome

Published version of a preprint

Abstract

BACKGROUND: The accuracy of microbial community surveys based on marker-gene and metagenomic sequencing (MGS) suffers from the presence of contaminants-DNA sequences not truly present in the sample. Contaminants come from various sources, including reagents. Appropriate laboratory practices can reduce contamination, but do not eliminate it. Here we introduce decontam ( https://github.com/benjjneb/decontam ), an open-source R package that implements a statistical classification procedure that identifies contaminants in MGS data based on two widely reproduced patterns: contaminants appear at higher frequencies in low-concentration samples and are often found in negative controls. RESULTS: Decontam classified amplicon sequence variants (ASVs) in a human oral dataset consistently with prior microscopic observations of the microbial taxa inhabiting that environment and previous reports of contaminant taxa. In metagenomics and marker-gene measurements of a dilution series, decontam substantially reduced technical variation arising from different sequencing protocols. The application of decontam to two recently published datasets corroborated and extended their conclusions that little evidence existed for an indigenous placenta microbiome and that some low-frequency taxa seemingly associated with preterm birth were contaminants. CONCLUSIONS: Decontam improves the quality of metagenomic and marker-gene sequencing by identifying and removing contaminant DNA sequences. Decontam integrates easily with existing MGS workflows and allows researchers to generate more accurate profiles of microbial communities at little to no additional cost.

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Integrity signals

Registry

Crossref · 10.1186/s40168-018-0605-2

Cites

58 of 58 references verified0 citation errors · 0 not checkable

Statistics

Claims the paper makes

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • External contaminants tend to have frequencies inversely correlated with sample analyte concentration and can be detected statistically.

    “recent literature demonstrated that external contaminants more consistently have frequencies inversely correlated with sample analyte concentration and can be detected using a robust statistical framework16,38.”
  • External contaminants were identified and removed using sample analyte concentrations and a blacklist of microbes from reagents in similar sequencing kits.

    “External contaminants were identified and removed using sample analyte concentrations for all TCGA samples (n=17,625), as recently described in the literature16,38, and by using a “blacklist” of microbes identified from reagents in sequencing kits similar to those used in TCGA14.”
  • A robust statistical framework recently validated the principle that contaminant frequencies are inversely correlated with sample analyte concentration.

    “A robust statistical framework recently validated this principle16, providing the opportunity to exploit sample DNA/RNA concentrations recorded by TCGA as a means to identify putative contaminants.”
  • Sequences from contaminants generally have frequencies inversely correlated with sample analyte concentration.

    “Additional putative external contamination was identified on the basis that sequences from contaminants generally have frequencies that are inversely correlated with sample analyte concentration16,38.”

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

The self-check needs the paper’s full text.

Cites

Flagged first, then by citations

Research works printed but not linked: 2

  1. [24]Kitchin PA Szotyori Z Fromholc C Almond N Avoidance of PCR false positives [corrected] Nature 1990 344 201 10.1038/344201a0 2156164 · DOI
  2. [50]Edgar RC. UNCROSS: filtering of high-frequency cross-talk in 16S amplicon reads: bioRxiv; 2016. p. 088666.

Cited by

Sorted by citations

Authors
Davis, N. M., Proctor, D. M., Holmes, S. P., Relman, D. A., & Callahan, B. J.
Affiliations
  • Stanford Medicine (US)
  • University of California, San Francisco (US)
  • Stanford University (US)
  • VA Palo Alto Health Care System (US)
  • North Carolina State University (US)
Corresponding author
Callahan, Benjamin J.
Venue
Microbiome
Published
2018-12
Volume
6
Issue
1
Pages
226-226
ISSN
2049-2618 (ISSN-L)
OpenAlex
W2952463830
Cited by
3,493
References
58
Citations by year
2026: 528 · 2025: 557 · 2024: 635 · 2023: 536 · 2022: 472 · 2021: 433 · 2020: 226 · 2019: 84 · 2018: 18 · 2017: 1 · 2015: 1
FWCI
67.86
Type
journal article
Language
en
Open access
Locations
  • Microbiome (publishedVersion, cc-by)
  • bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
  • National Institute of Dental and Craniofacial Research (R01 DE023113)
  • National Institute of Allergy and Infectious Diseases (R01 AI112401)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Genomics and Phylogenetic Studies
  • Physical Sciences › Environmental Science › Ecology › Microbial Community Ecology and Physiology
  • Physical Sciences › Environmental Science › Ecology › Environmental DNA in Biodiversity Studies
Keywords
pollutant removal, decontamination, metagenomics, marker gene sequencing, amplicon sequence variants, negative control, low-concentration samples, oral microbiota, preterm birth, microbial community analysis
MeSH terms
Bacteria, DNA, Bacterial, DNA, Ribosomal, Genetic Markers, Humans, Mouth, RNA, Ribosomal, 16S, Software, Models, Statistical, Sequence Analysis, DNA, Internet, Databases, Genetic, Metagenomics, DNA Contamination

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review