Metagenomic sequencing reveals high reproducibility of human donor microbiota transplanted into germ-free mice via lower gut route.

Human flora-associated (HFA) mice are often used to simulate the structure of human intestinal microbiota and to study the causal relationships between diseases and gut microbiota. However, several factors affect the colonization efficiency of human microbiota in germ-free (GF) mice, and the differential effects of gavage and lower gut transplantation on colonization are still unclear. In this study, we explored the reproducibility of the recipient-to-donor gut microbiota community structure and function under different transplantation routes and the differences in microbial colonization between recipients via gavage transplantation (GT_mice group) and lower gut transplantation (LGT_mice group). High-throughput sequencing of the metagenome was performed on the feces of each subject, and the composition of microbiome of each group was analyzed. As expected, the introduction of human fecal microbiota into GF mice via lower gut transplantation had a high transfer efficiency, which was evident from the similar species community structure to that of the donor (Adonis R2=0.713 960 for LGT_mice group‒donor group; Adonis R2=0.774 095 for GT_mice group‒donor group) and a higher bacterial colonization rate. The findings provide unique insights into improving the accuracy of constructing humanized microbiota transplantation models, aiding our understanding of the relationships between the human gut microbiota and disease.