title: Inherent bacterial DNA contamination of extraction and sequencing reagents may affect interpretation of microbiota in low bacterial biomass samples.
abstract: BACKGROUND
  The advent and use of highly sensitive molecular biology techniques to explore the microbiota and microbiome in environmental and tissue samples have detected the presence of contaminating microbial DNA within reagents. These microbial DNA contaminants may distort taxonomic distributions and relative frequencies in microbial datasets, as well as contribute to erroneous interpretations and identifications.
  
  
  RESULTS
  We herein report on the occurrence of bacterial DNA contamination within commonly used DNA extraction kits and PCR reagents and the effect of these contaminates on data interpretation. When compared to previous reports, we identified an additional 88 bacterial genera as potential contaminants of molecular biology grade reagents, bringing the total number of known contaminating microbes to 181 genera. Many of the contaminants detected are considered normal inhabitants of the human gastrointestinal tract and the environment and are often indistinguishable from those genuinely present in the sample.
  
  
  CONCLUSIONS
  Laboratories working on bacterial populations need to define contaminants present in all extraction kits and reagents used in the processing of DNA. Any unusual and/or unexpected findings need to be viewed as possible contamination as opposed to unique findings.
authors.affiliation: Department of Biological and Physical Sciences, Montana State University-Billings, 1500 University Drive, Billings, MT 59101 USA.
authors.forename: Angela
authors.initials: A
authors.lastname: Glassing
authors.affiliation: Molecular Research Laboratory (Mr. DNA), Shallowater, TX USA.
authors.forename: Scot E
authors.initials: SE
authors.lastname: Dowd
authors.affiliation: Hiram C. Polk, Jr. MD Department of Surgery, University of Louisville, Louisville, KY USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Galandiuk
authors.affiliation: Department of Surgery, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Davis
authors.affiliation: St. Vincent Healthcare, Sisters of Charity of Leavenworth Health System, Billings, MT USA ; Department of Biological and Physical Sciences, Montana State University-Billings, 1500 University Drive, Billings, MT 59101 USA.
authors.forename: Rodrick J
authors.identifier: 0000-0003-0580-7500
authors.initials: RJ
authors.lastname: Chiodini
keywords: 16S sequencing; Contamination; Inflammatory bowel disease; Metagenomics; Microbiota; PCR