Dietary Fat Quality and Sex Influence Diversity and Relative Abundance of the Colonic Bacterial Community Structure in Aged CD‐1 Mice
Authors: Unger Allison , Jetton Thomas , Kraft Jana 
Published: June 2021

Gut microbiota play a crucial role in disease pathogenesis. Evidence suggests that diet, sex, and aging are key factors that influence the intestinal microbiota community structure. Although many studies have examined the interaction of a high‐fat diet and the gut microbiota, little is known about the effect of dietary fat quality (e.g., fatty acid composition) or the role of sex on the gut microbiota in an aging population. Therefore, our study examined the effect of i) dietary fat quality, ii) sex, and iii) age on the colonic bacterial community structure. After one week of acclimation, 81 four‐week‐old male and female outbred CD‐1 mice (n=10/group) were fed 40% fat diets (kcal %) consisting of either (1) CON: 100% western‐style diet fat blend, (2) FO: 70% CON + 30% fish oil, (3) BO: 70% CON + 30% butter oil, or (4) EO: 70% CON + 30% echium oil until 14 months of age. Fecal collection (24 h) was carried out via metabolic cages at 10.5 and 13.5 months of age to compare the colonic bacterial community structure at mid‐life and geriatric time points, respectively. Microbial DNA was extracted and the bacteria‐specific primer pair 27F and 519R was used to amplify the V1–V3 region of the 16S rRNA gene. Amplicons were sequenced via the Illumina MiSeq (v.3) platform. The R package phyloseq was utilized to determine alpha and beta diversity. Relative abundance at the phylum and genus level as well as alpha diversity were analyzed with the PROC MIXED procedure with post hoc CONTRAST statements in SAS 9.4. Beta diversity was analyzed via MANOVA with the vegan package in R. Overall, males had a greater relative abundance of Firmicutes as well as a higher ratio of Firmicutes to Bacteriodetes than females (P < 0.05). However, in BO‐fed mice, Bacteriodetes increased in males but decreased in females upon aging, concomitant with a decreased prevalence of Firmicutes in males but an increase in females over time (P < 0.05). In general, females had a greater relative abundance of Alistipes (P < 0.05), while Lactobacillus exhibited a trend of increased prevalence in males (P = 0.0718). EO‐fed mice had a greater relative abundance of Blautia compared to FO‐ and BO‐fed mice (P < 0.05), while Lactobacillus indicated a trend of increased prevalence in FO‐fed mice (P = 0.0615). The relative abundance of Barnesiella increased upon aging regardless of diet or sex (P < 0.05). Alistipes increased in BO‐fed males but decreased in BO‐fed females over time (P < 0.05). EO‐fed mice displayed a trend of enhanced diversity compared to the other diet groups (observed species; P = 0.0582). Female mice had a greater alpha diversity (Shannon's Diversity Index) than males, yet males had a greater beta diversity (Bray‐Curtis) than females (P < 0.05). Our study establishes that dietary fat quality impacts the sex‐dependent alterations of the gut microbiota structure during aging.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.