Background: The gastrointestinal microbiota is a community of microorganisms that reside in the digestive tract.  Studies have suggested that the microbiota composition may contribute to the development of obesity and the metabolic syndrome.  Exercise has been shown to alter the microbiota composition by increasing diversity and altering specific bacteria species. We tested whether fecal microbiota transplantation (FMT) from exercise-trained mice to recipient mice alters body composition and metabolism.
Methods: C57BL6/J mice were fed a chow or high fat diet (HFD) for 4-weeks to induce obesity and insulin resistance. Mice were further divided into sedentary or exercise training groups (treadmill training for 6-weeks) while maintaining their respective diets (four groups of donor mice; chow sedentary or exercised and HFD sedentary or exercised).  Recipient mice were inoculated via oral gavage with the faeces from the respective donor groups once a week for 6-weeks and body composition and metabolism assessed.
Results: While the HFD led to glucose intolerance and obesity, exercise training resulted in a small decrease in body fat and improved glucose tolerance. FMT from the donor groups did not alter body composition (weight, fat mss, lean mass) in any of the recipient groups. Unexpectedly given the lack of an effect on adiposity, glucose tolerance was disrupted in the mice inoculated with faeces derived from mice on a HFD irrespective of exercise status and this was associated with a decrease in insulin-stimulated glucose clearance into white adipose tissue and the large intestine.
Conclusion: FMT can transmit HFD-induced aspects of disrupted glucose metabolism to recipient mice independently of any change in adiposity. However, FMT from exercise trained donor mice appears to elicit no beneficial effect.  
Disclosure: No conflict of interest