Biodiversity of Human Gut Methanogens Varies With Concentration of Exhaled Breath Methane: 1256

Introduction: Methane producing Archaea (MPA), or methanogens, are implicated in pathogenic GI disorders in humans including inflammatory bowel disease, gastrointestinal (GI) cancer, IBS, anorexia and obesity. Measurement of the concentration of breath Methane has been considered to be an accurate surrogate for the presence of MPA in the colon. We used quantitative real-time PCR, utilizing primers for methyl-coenzyme M reductase subunit (mcrA). An Inverse relationship to MPA biodiversity and breath methane in normal individuals was observed. Unique Archaea species were found in the most diverse stool samples found in low Methane emitters. Methods: Stool samples from the 5 highest and 5 lowest breath methane producers were evaluated. Medical and family history, ROME III questionnaire, BMI and demographics were recorded. Stool samples were collected in standard 50 mL sample containers and fixed in 70% ethanol solution. Genomic DNA was then extracted using the RBB+C method (Yu & Morrison, 2004). Subjects provided 3 alveolar breath samples without fasting or specifically consuming carbohydrate. The Quintron Breath Tracker SC was used to measure NEBM measurements. Stool samples were analyzed using real-time PCR to determine the density of methanogens in the extracted DNA using PCR primers, mcrA-F and mcrA-R, targeting the methyl-coenzyme M reductase subunit.Figure 1Figure 2Figure 3Results: 10 subjects are reported: 15 M, 17F. Age: mean 37 years (18-55), BMI: mean 26 (19-35). Although MPA were present in all subjects by RT-PCR, biodiversity varied depending on exhaled Methane concentration. High Methane emitting subjects had stool MPA present which were almost exclusively populated with Methanobrevibacter smithii. Considerable biodiversity in MPA species was observed in stool samples from the low Methane emitting subjects. Analysis of the various species of MPA in the low Methane emitters revealed species which were not previously described in humans, but have been sequenced from soil and in ruminant mammals. Results were independent of age, race, BMI, gender, or family history of colorectal cancer. Conclusion: Breath Methane concentration is inversely associated with MPA Biodiversity. It is likely that in individuals with low breath Methane, Archaea species other than M. smithii are present and these species compete for methanogenic precursors (ex. Carbon, hydrogen) in the gut. Previously, reduced gut bacterial diversity has been associated with pathology.