Effect of Probiotic Yogurt Consumption on Colon Metabolome in C57BL6 Mice  

Haley Chatelaine
Graduate (PhD)
Rachel Kopec (OSU Nutrition Program)

Probiotic yogurt consumption is associated with beneficial gut health, including nutrient production and immune regulation, largely via gut microbiome modulation. However, metabolites that mediate host-microbiome interactions are largely unknown. 
Hypothesis: Consumption of probiotic yogurt during adolescence results in distinct metabolic signatures in colon, including decreased levels of branched-chain amino acids, triglycerides, and bile acids, relative to probiotic-free yogurt, milk, and water controls. Further, these differences are driven by increased abundances of Lactobacilli and Bifidobacteria following probiotic yogurt consumption. 
Methods: Mice (3 weeks old, C57BL6, n = 32 male, 32 female) were fed AIN-93G for 3 weeks, followed by 3 weeks of daily gavage of 150 µL probiotic yogurt (PY), heat-inactivated yogurt (HY), milk (M), or water (W). Polar and nonpolar colon extracts were analyzed with ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS) and 1H NMR. Features detected with 1H-NMR and C18 and C8 LC-MS in positive mode were compared, pairwise, between diet groups.
Results: Metabolite classes detected via UHPLC-HRMS included bile acids, amino acids, phospholipids. NMR yielded the following number of features with an absolute log2-fold change gt; 2 and unadjusted P-value lt; 0.05 between dietary groups: 74 (PY v HY), 17 (PY v M), 57 (PY v C), 79 (HY v M), 14 (HY v C), and 47 (M v C), and C18 and C8 LC-MS in positive mode (using the same cutoffs used in NMR): 349 (PY v HY), 73 (PY v M), 307 (PY v C), 15680 (HY v M), 86 (HY v C), and 121 (M v C). 
Conclusions: As hypothesized, probiotic yogurt consumption significantly altered the colon metabolome relative to controls. Metabolite identification, pathway enrichment analysis, and next generation microbiome sequencing analyses will aid in identifying specific microbiome-associated pathways altered upon PY consumption. Ultimately, this