Microbial community composition in the dung of five sympatric European herbivore species

The dung microbiome is a complex system that is highly influenced by species and diet. This study characterized the dung bacterial and fungal communities of five herbivore species inhabiting the National Park Zuid-Kennemerland, the Netherlands. The five selected herbivore species were rabbit ( Oryctolagus cuniculus L.), cow ( Bos taurus L.), horse ( Equus ferus caballus L.), fallow deer ( Dama dama L.), and European bison ( Bison bonasus L.). We explored the effects of distinct digestive physiology (ruminants vs. non-ruminants) and diverse dietary preferences on the microbial community composition of herbivore dung. Firmicutes and Bacteroidetes were dominant bacterial phyla in the dung of all five herbivore species, and Ascomycota was the predominant fungal phylum. Verrucomicrobiota and Mucoromycota were more present in horse dung and Proteobacteria were more abundant in rabbit dung than the three ruminant dung types. There were few significant differences in the microbial community structure among the three ruminant dung types. The alpha and beta diversity of dung microbial communities significantly differed between ruminants and non-ruminants, especially in bacterial communities. Based on MetaCyc pathways, we found that the primary functions of bacteria in herbivore dung were focused on biosynthesis, various super pathways, and degradation, with a few differences between ruminant and non-ruminant dung. FUNGuild analysis showed that horse dung had more saprotrophic fungi, while the fungi in fallow deer dung had more symbiotrophic properties, with the fungal functions of bison, cow, and rabbit dung somewhere in between. There was also a correlation between microbial community and nutrient composition of the substrate in herbivore dung. Understanding the dung microbial community composition of these herbivore species can enrich the database of mammalian gut microbiomes for studying the mechanisms of microbial community variation while preparing for exploring a new perspective to study the impact of herbivores on ecosystems through dung deposition.