A comparison of the microbiome and the metabolome of different regions of the equine hindgut.

This research paper studies the differences between the microbiome (the microorganisms in a particular environment) and metabolome (the complete set of small-molecule metabolites) in different areas of the horse’s hindgut. The study suggests that fecal samples may not fully represent the microbiome of certain hindgut regions like the caecum, which might have implications for scientific investigations of the horse’s digestive system.

Microbial Population Community Structure and Their Functional Metabolic Products

• The study compares the microbiome and metabolome of fecal samples to those from the caecum and right dorsal colon of horses. The key method of comparison was the investigation of the microbial population community structure and their functional metabolic products.
• 16S rRNA gene dendrograms were used to illustrate the distinct microbiome of the caecum, which was found to cluster separately from the other gut regions. The 16S rRNA gene-based quantitative PCR (q-PCR) also underlined these differences.
• By using Fourier transform infrared (FTIR) spectroscopy, metabolites were identified and found to show a similar pattern of clustering, reinforcing that microbial composition and metabolites vary across different gut regions.

Protozoal and Archaeal Concentrations

• Using q-PCR, the concentration of protozoal 18S rDNA and archaeal mcrA gene were quantified and found in higher numbers in the colon compared to other gut regions.

Diversity Assessments

• Diversity in the horse’s gut was quantified using the Simpson and Shannon-Wiener indices. These calculations revealed higher diversity of bacteria in the right dorsal colon and feces than in the caecum.

Implications

• Collectively, the results suggest that fecal samples likely represent the microbial population of the right dorsal colon to some extent but not that of the caecum.
• This implies that careful consideration is necessary when planning microbial investigations of the hindgut of the horse, as the microbial population and metabolic products can significantly vary across different parts of the hindgut.