Rumen Microbes

Learn more about the role of the rumen and lower gut microorganisms and their impact on the host’s performance, nutrition, and health. The ruminant is a fascinating animal due to its ability to convert feed and forage into energy and microbial protein thanks to the activity of its gut microbial community: bacteria, archaea, protozoa, and fungi. This page features microbes found in the gut of ruminants.

Eubacterium ruminantium

The rumen ecosystem provides an ideal environment for different populations of microorganisms. The microbial populations interact through various strategies such as mutualism (benefits for both microorganisms), commensalism (benefits for one without influencing the other), parasitism (benefits for one at a disadvantage for the other), and competition (several microorganisms compete for substrates or space), allowing the ruminant to obtain the essential nutrients for its nutrition through microbial fermentation processes. For this reason, the maintenance of stable ruminal conditions (pH, temperature, etc.) allows the growth of these microbial populations in order to have a better fermentation.

The featured microbe this month is Eubacterium ruminantium. On this occasion, we will learn its general characteristics and functions to better understand its importance for rumen activity and the animal.

Click or hover over the top of the image hotspots​ to learn more about this featured microbe. ​​

This interactive image was created by Alison Pfau.

(Photo Courtesy of Tri-State Livestock News)

For additional information, please contact Dr. Phillip Myer.

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Image depicting the structure of Gram positive and negative bacteria

The genus Eubacterium is an anaerobic, Gram-positive microbe that produces carbon dioxide and organic acids, such a butyric, acetic, formic, and lactic acids from various sugars. Image adapted from

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Image of cellulose in plants

Eubacterium ruminantium makes important contributions to plant fiber degradation, specifically, hemicellulose digestion (mainly xylan, by the action of xylanase enzymes) found in plants and in all cell walls of grasses. Image adapted from

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Depiction of fatty acids in the rumen

E. ruminantium also has the function of converting unsaturated fatty acids to more saturated fatty acids in the gut, which is important for fiber breakdown in the rumen. Image adapted from

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Image of cattle eating with a chart of bacterial percentages

Eubacterium ruminantium are common microbes in the bovine rumen on hay diets, but not prevalent within animals on concentrate diets. Image adapted from Kim. Y.H et al., 2018 and Troy Walz, University of Nebraska-Lincoln, 2018

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Chart depicting xylanase enzyme activity in response to pH

The enzymatic activity of Eubacterium ruminantium decreases when the pH in the rumen is not favorable. Image adapted from Taguchi et al., 2004.

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This work is supported by the Agriculture and Food Research Initiative Competitive grant no. 2020-67015-30832 / project accession no. 1021775 from the USDA National Institute of Food and Agriculture.