Researchers Assemble Genomic "Jigsaw" of Cow Gut Microbes
Using high-tech tools, Agricultural Research Service (ARS) scientists and their cooperators have taken a deep dive into the microbial "soup" of the cow's rumen, the first of four stomach chambers where tough plant fibers are turned into nutrients and energy.
"Compositionally, the rumen is unique because it contains organisms from all three kingdoms of life: Bacteria, Archaea and Eukaryotes. All of these organisms work in tandem to consume plant matter, and the byproducts of their digestion are used by the cows to produce meat and milk," explained Bickhart, who is at the ARS center's Cell Wall Biology and Utilization Research Unit. Bickhart estimated there are over 30,000 species of these rumen dwellers, yet fewer than a couple thousand have been adequately characterized. That's left a gap in researchers' understanding of what role each species plays as part of a larger community known as the "microbiome." Researchers also want to learn what a microbe's absence or even proliferation can mean to the cow's wellbeing and performance—from withstanding costly diseases like mastitis, to producing important milk fats.
The team's use of its specialized DNA extraction and sequencing procedures also revealed new insights about another denizen of the cow rumen, namely "bacteriophages"—viruses that highjack the genomes of bacteria to replicate themselves. In all, the team identified 188 bacteria-phage interactions, including host preferences, lifecycle and impacts on the microbe's metabolic activity. "On the direct application side, knowledge of the rumen microbial community will be critical to estimating the feed efficiency of cattle and identifying microbes that contribute directly to milk fat production," said Bickhart.