Date of Award:

8-2018

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Animal, Dairy, and Veterinary Sciences

Committee Chair(s)

Abby D. Benninghoff

Committee

Abby D. Benninghoff

Committee

Korry J. Hintze

Committee

Kerry A. Rood

Abstract

The composition of the gut microbiome can be affected by environmental factors, such as diet. The Western dietary pattern is associated with microbiome dysbiosis and adverse health outcomes, including obesity and metabolic disorders. The objective of this study was to examine the effect of gut microbiota from lean or obese human donors on metabolism and weight gain in recipient mice fed one of three basal diets: 1) the standard AIN93G diet, which promotes rodent health; 2) the total Western diet (TWD), which mimics the American dietary pattern and promotes inflammation-associated colorectal carcinogenesis; and 3) a 45% high fat diet-induced obesity (DIO) diet, which promotes excessive weight gain and symptoms of metabolic syndrome. We hypothesized that fecal microbiome transfer (FMT)from obese human donors would lead to an obese phenotype with symptoms of metabolic syndrome in recipient mice, and that consumption of TWD or DIO diets would further exacerbate the metabolic syndrome phenotype. The experiment design consisted of two main factors: body type of the human donor (obese or lean) and experimental diet (AIN, DIO or TWD), which was fed to mice for 22 weeks. Prior to FMT, the resident gut microbiome in mice was depleted using an established broad spectrum antibiotic/antifungal oral dosing regimen. Interestingly, human donor body type did not significantly affect final body weight or body composition in recipient mice fed any of the experimental diets. Beta diversity analysis, which assesses the distinctiveness of different organism populations, showed that obese recipient mice had a significantly different fecal microbiome compared to lean recipient mice. Other statistical analyses identified several bacteria taxa that distinguished microbiomes for obese FMT recipients compared to lean FMT mice. However, diet also influenced the microbiome composition irrespective of donor body type, suggesting that diet is a key variable in the shaping of the gut microbiome over a prolonged period. In conclusion, body type of human donors used for FMT did not alter the phenotype of recipient mice with respect to body weight gain or metabolic syndrome symptoms despite recipient mice having distinct fecal microbiomes.

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