Microbial composition and viability in equine feces after processing for transplantation

Fecal microbiota transplantation has been used empirically for decades in equine medicine but evidence
based information on this technique is scarce. This in vitro study aimed to assess the effect of a common
fecal pre-transplantation processing method on microbiota composition and viability of the fecal
inoculum.
A fresh equine fecal sample was divided in three 300g aliquots, to be processed identically as follows:
feces (T ) were mixed with 1 L of lukewarm water and chopped using an immersion blender to obtain a
mixture (T ), which was left uncovered during 30 minutes (T ) and filtered through a sieve to obtain a
fecal infusion (T ). Samples were taken at different steps of the procedure (T ) and immediately stored at
4°C < 6 hours until processing. Bacterial 16S rDNA amplicon profiling associated to propidium-monoazide
treatment was performed in each of the 12 samples to select living bacteria. Total flora was measured
using quantitative PCR analysis. Bacterial community structure, composition and total flora were
statistically compared (significance p < 0.05).
No significant differences in ecological indices or abundance of the major bacterial genera were
identified for the different steps of fecal processing. Estimated total flora (mean ± SD) in the final fecal
infusion was not significantly lower (10.06 ± 0.07 log gene copies/g) than in the original manure (10.29 ±
0.3 log gene copies/g). Results were similar for all three fecal aliquots.
These results suggest that the processing method described in this study is replicable and the resultant
fecal inoculum contains live bacteria and a microbial population similar to the original fecal sample.