Characterization of Fecal Gut Microbial Composition and Function in a State of Physical Activity and Excess Energy Intake

Abstract

Despite public health initiatives at the global, national, and state levels, the prevalence of obesity continues to grow. Alterations in gut microbial composition have been observed in individuals with obesity. Changes in the composition of the gut microbiota may correspond to changes in the functional composition and can impact metabolite availability to the host. Although physical activity is a key lifestyle intervention for obesity treatment and management, its effect on the gut microbiota remains poorly understood. Therefore, we investigated the impact of 12-week moderate treadmill exercise on the gut microbiota of two cohorts of male C57BL/6 mice fed a high-fat, high-sugar (HFHS), or standard chow diet (LN). In the first cohort, fecal samples were collected only at the end of the intervention and were sequenced using shallow shotgun sequencing. In the second cohort, both pre-and post-test fecal samples were collected and analyzed using gas chromatography-mass spectrometry for short-chain fatty acid quantification and deep shotgun sequencing for microbial characterization. In both studies, mice in the HFHS-fed group gained significantly more weight than LN mice, and changes in gut microbial diversity and taxonomy tended to correspond to diet rather than exercise assignment. Furthermore, the implementation of a mixed-effects model in the second cohort indicated that changes at the phylum level were driven by time, while changes at the species level were driven by diet. Exercise increased the abundance of Faecalibaculum rodentium, whose abundance positively correlated with the majority of enzymes involved in branch-chain amino acid biosynthesis. Overall, our results support the ability of a Western-style diet to alter microbial composition and provide insight into the taxonomic and functional changes occurring in response to exercise.