Methanogenic community structure in the digestive tract of Equidae

This study aims to assess the diversity of the methanogenic community in six different segments hindgut (cecum, four different tracts of the colon and rectum) of two equides (horse and donkey). The archaeal genomic DNA was isolated from two adult animals and a clone library for each segment was built. All the positive clones were further analysed with the RFLP (Restriction Fragment Length Polymorphism) using the restrictases MluI and MboI and the representatives of the different restriction patterns underwent the sequence analysis. The phylogenetic analysis revealed interesting differences among the different parts of the digestive tract of each animal and considerable diversity between these two species. The diversity of the hindgut methanogen population was higher in the horse compared to the donkey. In the horse the phylogenetic analysis showed that the clones were classified in 4 clades: Methanobacteriales, Methanomicrobiales, Methanomassiliicoccales and Methanosarcinales. The clones of the donkey were classified in 3 clades: Methanobacteriales, Methanomassiliicoccales and Methanomicrobiales. The abundance and the distribution of the methanogens differed greatly in the two animals, while the methanogen community structure was quite similar, with the dominance of Methanomicrobiales and Methanobacteriales. This finding indicates that the hydrogenotrophic methanogenesis is the major methane production pathway in the hindgut of both the two species.