Cattle (Steer) Rumen breed:Simmental by Angus Crossbred Metagenome. bovine gut metagenome strain:Animal 1 (Lane 5-6) | breed:Simmental by Angus Crossbred

The symbiotic microbes of ruminant animals allow these animals to subsist off of diets indigestible to other vertebrates. But while the biochemical outlines of this feat are known, how a microbial ecosystem can be both efficient and flexible enough to maintain this adaptation is not well understood. Here we move beyond taxonomic approaches to microbial ecology and consider the enzymes present in these environments. We shotgun sequenced two rumen metagenomic samples, obtaining more than 60 million sequence reads. Comparing those reads to a database of more than half a million enzymes allowed us to identify 1.2 million distinct enzyme-coding genes in the samples. We then used a novel metabolic network bi-partitioning approach to link the identified enzymes to the host’s metabolism.