Abstract
Objectives
Gut microbiota profiles contribute to differences in obesity phenotype. The contribution of specific bacterial species has not been shown. In two sequential studies, we examined the abundance of total bacteria, and the species Clostridium butyricum in relation to the propensity of outbred Sprague-Dawley CD rats to accumulate abdominal fat. As a probiotic, C. butyricum is associated with enhanced butyrate production, reduced inflammation and prevention of diet induced weight gain. Outbred CD rats have two obesity phenotypes; obese‐resistant rats (OR) remain lean while obese‐prone (OP) rats develop obesity within 4 weeks when fed the same high calorie diet.
Hypothesis: Propensity of Outbred CD rats to gain fat correlates with abundance of specific bacterial species.
Methods
In study I, we fed both OP (N = 32) and OP rats (N = 32) either a low fat (LF) diet, a high fat diet (HF) or a HF diet supplemented with Resistant starch (RS). In study II, we fed all rats; OP (N = 28) and OR (N = 28) a HF diet supplemented with RS and 4 weeks later, after administering antibiotics we performed a microbiota transplant between the two phenotypes. We evaluated the bacterial profile and fat accumulation.
Results
As expected OP rats gained fat while OR rats remained lean; P < 0.002 in both studies (Fig 1). Total bacteria were higher in OR rats before including RS in the diet. When RS was included in the diet, robust fermentation coupled with increase in total bacteria was observed only in OP rats. Species from family Clostridiaceae and particularly C. butyricum were higher in OR rats irrespective of diet (P < 0.005 in study I; P < 0.0001 in study II) (Fig 2). Dietary RS and the microbiota transplant had no effect on abundance of C. butyricum and did not induce phenotype changes. Antibiotics reduced total bacteria and 4 weeks later total bacteria levels were restored but, C. butyricum levels remained lower.
Conclusions
The saccharolytic C. butyricum does not ferment RS. C. butyricum may be one of the species that constitute a core microbiota associated with the lean phenotype and is involved in mechanisms that impact energy consumption or storage, and appetite regulation through mechanisms that are not yet known.
Funding Sources
Louisiana State University Agricultural Center (NIFA 94268). The starches were gifts from Ingredion Incorporated.
Supporting Tables, Images and/or Graphs
Clostridium butyricum affects nutrition and immunology by modulating gut microbiota
