title: Assessing the colonic microbiome, hydrogenogenic and hydrogenotrophic genes, transit and breath methane in constipation.
abstract: BACKGROUND
  Differences in the gut microbiota and breath methane production have been observed in chronic constipation, but the relationship between colonic microbiota, transit, and breath tests remains unclear.
  
  
  METHODS
  In 25 healthy and 25 constipated females we evaluated the sigmoid colonic mucosal and fecal microbiota using 16S rRNA gene sequencing, abundance of hydrogenogenic FeFe (FeFe-hydA) and hydrogenotrophic (methyl coenzyme M reductase A [mrcA] and dissimilatory sulfite reductase A [dsrA]) genes with real-time qPCR assays, breath hydrogen and methane levels after oral lactulose, and colonic transit with scintigraphy.
  
  
  RESULTS
  Breath hydrogen and methane were not correlated with constipation, slow colon transit, or with abundance of corresponding genes. After adjusting for colonic transit, the abundance of FeFehydA, dsrA, and mcrA were greater (P<.005) in colonic mucosa, but not stool, of constipated patients. The abundance of the selected functional gene targets also correlated with that of selected taxa. The colonic mucosal abundance of FeFe-hydA, but not mcrA, correlated positively (P<.05) with breath methane production, slow colonic transit, and overall microbiome composition. In the colonic mucosa and feces, the abundance of hydrogenogenic and hydrogenotrophic genes were positively correlated (P<.05). Breath methane production was not associated with constipation or colonic transit.
  
  
  CONCLUSIONS
  Corroborating our earlier findings with 16S rRNA genes, colonic mucosal but not fecal hydrogenogenic and hydrogenotrophic genes were more abundant in constipated vs. healthy subjects independent of colonic transit. Breath gases do not directly reflect the abundance of target genes contributing to their production.
authors.affiliation: Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
authors.forename: P G
authors.initials: PG
authors.lastname: Wolf
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, MN, USA.
authors.forename: G
authors.initials: G
authors.lastname: Parthasarathy
authors.affiliation: Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA.
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.affiliation: Clinical Research and Trials Unit, Center for Clinical and Translational Science, Rochester, MN, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: O'Connor
authors.affiliation: Division of Biomedical Statistics and Informatics, Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA.|Microbiome Program, Center for Individualized Medicine, Rochester, MN, USA.
authors.forename: N
authors.initials: N
authors.lastname: Chia
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Medicine, Mayo Clinic, Rochester, MN, USA.
authors.forename: A E
authors.identifier: http://orcid.org/0000-0002-7644-0390
authors.initials: AE
authors.lastname: Bharucha
authors.affiliation: Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, USA.|Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
authors.forename: H R
authors.initials: HR
authors.lastname: Gaskins
mesh_terms: D000328:Adult; D001944:Breath Tests; D003248:Constipation / Q000382:microbiology* / Q000503:physiopathology*; D004269:DNA, Bacterial / Q000032:analysis; D005260:Female; D000069196:Gastrointestinal Microbiome / Q000502:physiology*; D005772:Gastrointestinal Transit / Q000502:physiology; D006801:Humans; D008697:Methane / Q000032:analysis*; D008875:Middle Aged
chemical_list: D004269:DNA, Bacterial; D008697:Methane
keywords: breath hydrogen; breath methane; constipation; genes; hydrogen; lactulose; methane; microbiome; microbiota; transit