A comparison of methanogens of different regions of the equine hindgut.

This research investigates the varying distribution of methane-producing microorganisms, methanogens, in different areas of the hindgut in horses and donkeys, using DNA analysis techniques.

Methodology

• The study examined the diversity of methanogenic archaea – single-celled microorganisms that produce methane as a metabolic byproduct – in six distinct parts of the equine hindgut. These included the caecum, right ventral colon, left ventral colon, left dorsal colon, right dorsal colon, and rectum.
• A 16S rDNA gene clone library was used for this analysis. The 16S rDNA is a part of the bacterial DNA that is distinctively different for different species of bacteria, making it a suitable tool for identifying and comparing bacteria.

Findings

• From the analysis, 641 clones were found positive, with 321 from the horse and 320 from the donkey’s hindgut.
• The Restriction Fragment Length Polymorphism (RFLP) technique was then used to analyse these clones – a technique in genetic research that allows differentiation between different organisms based on their distinctive patterns of fragment lengths in DNA cuts by specific enzymes.
• Nine distinct ribotypes were uncovered, with eight found in the horse, and five in the donkey's hindgut.
• Two dominant orders of Methanobacteriales (with Methanobrevibacter-like sequences) and Methanomicrobiales (with Methanocorpusculum-like sequences) were found in both animals.
• Methanomassiliicoccales, another order of archaea, was found but in lesser quantities.

Impact of Gut Region on Archaeal Composition

• An interesting finding was that the composition of the equine archaeal community appeared to be influenced by the specific region of the gut.
• For instance, no Methanobrevibacter-like clones were found in the caeca (the first part of the large intestine) of both animals, which were instead inhabited by Methanocorpusculum-like archaeons.
• The Methanosarcinales, a different kind of methanogen, was only found in the more distal regions of the horse’s hindgut.

Implications

• The results of this study show that the microbiome of the equine hindgut is greatly diversified and influenced by the specific region of the gut. This should be taken into consideration in further studies about equine gut microbiota and also for the development of dietary strategies intended to modulate gut microbiota.