The Effects of Dietary 25-Hydroxyvitamin D3 Supplementation from Synthetic Supplement or Biofortified Egg Yolks on Colonic and Fecal Microbiome in Mice Consumed Control or High-Fat Diets.

Forty-eight Reg2+/- adult mice were allocated to six dietary treatment groups (n = 8) with a 2-by-3 factorial experiment design: 2 levels of dietary fat (control diet, CON; or high-fat diet, HFD) supplemented with 3 different levels and sources of 25-hydroxyvitamin D3 treatments: 200 IU per kg of feed from control yolks as basal (BAS), 700 IU/kg from synthetic supplement (SUP), or 700 IU/kg from biofortified egg yolks (YOL). At the end of this 8-week study, fresh fecal samples (2-3 pellets) one day prior to euthanasia as well as colonic contents after euthanasia were collected from individual animals. About 150 mg of colonic content or fecal samples were used for genomic DNA extraction, and the V5-V5 region of the 16S rRNA gene was amplified by using uniquely barcoded universal reverse primer 926R. Equal amounts of the final purified amplicon were pool together and sequenced using MiSeq Illumina 300 cycles paired-end option. The QIIME2 pipeline and DADA2 were utilized to process the sequencing reads, and the GreenGenes database was employed for taxa identification. The beta diversity, alpha diversity, and the microbial compositions were examined.