RT Journal Article
SR Electronic
T1 Composition and energy harvesting capacity of the gut microbiota: relationship to diet, obesity and time in mouse models
JF Gut
JO Gut
FD BMJ Publishing Group Ltd and British Society of Gastroenterology
SP 1635
OP 1642
DO 10.1136/gut.2010.215665
VO 59
IS 12
A1 E F Murphy
A1 P D Cotter
A1 S Healy
A1 T M Marques
A1 O O'Sullivan
A1 F Fouhy
A1 S F Clarke
A1 P W O'Toole
A1 E M Quigley
A1 C Stanton
A1 P R Ross
A1 R M O'Doherty
A1 F Shanahan
YR 2010
UL http://gut.bmj.com/content/59/12/1635.abstract
AB Background and Aims Increased efficiency of energy harvest, due to alterations in the gut microbiota (increased Firmicutes and decreased Bacteroidetes), has been implicated in obesity in mice and humans. However, a causal relationship is unproven and contributory variables include diet, genetics and age. Therefore, we explored the effect of a high-fat (HF) diet and genetically determined obesity (ob/ob) for changes in microbiota and energy harvesting capacity over time. Methods Seven-week-old male ob/ob mice were fed a low-fat diet and wild-type mice were fed either a low-fat diet or a HF-diet for 8 weeks (n=8/group). They were assessed at 7, 11 and 15 weeks of age for: fat and lean body mass (by NMR); faecal and caecal short-chain fatty acids (SCFA, by gas chromatography); faecal energy content (by bomb calorimetry) and microbial composition (by metagenomic pyrosequencing). Results A progressive increase in Firmicutes was confirmed in both HF-fed and ob/ob mice reaching statistical significance in the former, but this phylum was unchanged over time in the lean controls. Reductions in Bacteroidetes were also found in ob/ob mice. However, changes in the microbiota were dissociated from markers of energy harvest. Thus, although the faecal energy in the ob/ob mice was significantly decreased at 7 weeks, and caecal SCFA increased, these did not persist and faecal acetate diminished over time in both ob/ob and HF-fed mice, but not in lean controls. Furthermore, the proportion of the major phyla did not correlate with energy harvest markers. Conclusion The relationship between the microbial composition and energy harvesting capacity is more complex than previously considered. While compositional changes in the faecal microbiota were confirmed, this was primarily a feature of high-fat feeding rather than genetically induced obesity. In addition, changes in the proportions of the major phyla were unrelated to markers of energy harvest which changed over time. The possibility of microbial adaptation to diet and time should be considered in future studies.