# Effect of Shipping on the Microbiome of Donor Mice Used to Reconstitute Germ-Free Recipients

## TL;DR

Shipping donor mice affects their gut microbiome, which can be transferred to germ-free mice through fecal transplants, but the impact varies by supplier.

## Contribution

The study reveals that shipping-induced microbiome changes in donor mice can be transmitted to germ-free recipients, with supplier-specific patterns.

## Key findings

- Shipping alters the donor microbiome in a supplier-dependent manner.
- FMT transmits shipping-induced microbiome changes to germ-free recipients.
- Supplier-origin microbiome effects persist despite shipping-induced changes.

## Abstract

The gut microbiome (GM) influences multiple processes during host development and maintenance. To study these events, fecal microbiota transfer (FMT) to germ-free (GF) recipients is often performed. Mouse models of disease are also susceptible to GM-dependent effects, and cryo-repositories often store feces from donated mouse strains. Shipping live mice may affect the GM and result in an inaccurate representation of the baseline GM. We hypothesize that the use of such fecal samples for FMT would transfer shipping-induced changes in the donor GM to GF recipients. To test this, donor mice originating from two suppliers were shipped to the University of Missouri. Fecal samples collected pre- and post-shipping were used to inoculate GF mice. Pre- and post-shipping fecal samples from donors and fecal and/or cecal contents were collected from recipients at 1 and 2 weeks post-FMT. 16S rRNA sequencing revealed supplier-dependent effects of shipping on the donor microbiome. FMT efficiency was independent of shipping timepoint or supplier, resulting in the transmission of shipping-induced changes to recipient mice; however, the effect of supplier-origin (SO) microbiome remained evident. While shipping may cause subtle changes in fecal samples collected for FMT, such effects are inconsistent among SO GMs and minor in comparison to other biological variables.