Voluntary and forced exercise differentially alters the gut microbiome in C57BL/6J mice

We have previously shown that voluntary wheel running (VWR) attenuates, whereas forced treadmill running (FTR) exacerbates, intestinal inflammation and clinical outcomes in a mouse model of colitis. As the gut microbiome is implicated in colitis, we hypothesized that VWR and FTR would differentially affect the gut microbiome. Mice (9-10/treatment) were randomly assigned to VWR, FTR, or sedentary home cage control (SED) for 6 wk. VWR were given running wheel access, whereas FTR ran on a treadmill for 40 min/day at 8-12 m/min, 5% grade. Forty-eight hours after the last exercise session, DNA was isolated from the fecal pellets and cecal contents, and the conserved bacterial 16S rRNA gene was amplified and sequenced using the Illumina Miseq platform. Permutational multivariate analysis of variance based on weighted UniFrac distance matrix revealed different bacterial clusters between feces and cecal contents in all groups (P < 0.01). Interestingly, the community structures of the three treatment groups clustered separately from each other in both gut regions (P < 0.05). Contrary to our hypothesis, the α-diversity metric, Chao1, indicated that VWR led to reduced bacterial richness compared with FTR or SED (P < 0.05). Taxonomic evaluation revealed that both VWR and FTR altered many individual bacterial taxa. Of particular interest, Turicibacter spp., which has been strongly associated with immune function and bowel disease, was significantly lower in VWR vs. SED/FTR. These data indicate that VWR and FTR differentially alter the intestinal microbiome of mice. These effects were observed in both the feces and cecum despite vastly different community structures between each intestinal region.