The fecal microbiota of semi-free-ranging wood bison (Bison bison athabascae)

The intestinal tract harbours a complex and diverse microbial population that is important for health, yet has been poorly described in many species. This study explored the fecal microbiota of semi-free-ranging Wood bison (Bison bison athabascae).

A total of 2081936 16S rRNA (V4) sequences from 40 bison were evaluated. CatchAll analysis of richness predicted a mean of 10685 species per sample (range 5428-24764, SD 4136). Diversity was high, with an average inverse Simpson's index of 31.78 (SD 15.3, range 8.55-86.7). Twenty-one different phyla were identified; however, only Firmicutes and Proteobacteria, Actinobacteria accounted for >1% of sequences. Two distinct population clusters (Group A, n = 19 and Group B, n = 21) were evident based on both community membership and population structure. Group A had a significantly lower relative abundance of Actinobacteria (6.4 vs 11.8%, P = 0.002), Chloroflexi (0.002 vs 0.013%, P = 0.014), Gemmatimonadetes (0.007 vs 0.15%, P = 0.038) and Proteobacteria (18.7 vs 42.5%, P = <0.0001) and a greater relative abundance of Firmicutes (70.9 vs 39.3%, P < 0.0001) than Group B. Within Group B, Alphaproteobacteria was the most common class of Proteobacteria (28% of all sequences), while Caulobacteraceae (18.5%), Pseudomonadaceae (3.5%), Hyphomicrobiaceae (3.5%), Alcaligenaceae (3.1%) and Xanthomonadaceae (2.6%) were the most abundant families. The twenty (3.1%) most abundant genera accounted for 71% of sequences. No operational taxon units (OTUs) were found in all samples at a relative abundance of 1% or greater. One OTU (Clostridium cluster XI) was present at 1% or more in all Group A samples, with two other Clostridium cluster XI OTUs in 18/19 (95%) samples. No OTUs were found at that abundance in all Group B sample, but an unclassified Lachnospiraceae was present in 20/21 (95%) and Clostridium cluster XI and Brevundimonas were found in 19 (90%) samples.

The fecal microbiota of Wood bison is rich and diverse. The presence of two distinct populations not associated with housing, age or gender suggest that enterotypes, distinctly different microbial population compositions that can achieve the same ultimate function, might be present in bison, as has been suggested in humans.