Newly Discovered Gut Microbe Structure May Explain Cow Methane Emissions
Scientists have identified a previously unknown cell structure in cow gut microbes that could explain why cattle produce so much methane. The structure, dubbed the 'hydrogenobody,' was found in rumen ciliates and produces hydrogen that other microbes convert into methane. The study, published in Science on April 30, analyzed DNA from 450 ciliates in cattle, sheep, goats, and deer, revealing 65 species (45 with previously unexamined genomes). In 100 dairy cows, higher ciliate counts correlated with more methane-producing microbes and greater emissions. In sheep, the ciliate genus Dasytricha was particularly abundant in high-methane emitters—up to 100 times more than low emitters. Dasytricha cells contain about 28 times more hydrogenobodies than the lower-methane genus Entodinium. Unlike the related hydrogenosome, hydrogenobodies have only one membrane, suggesting different evolutionary origins. The discovery offers a 'mechanistic breakthrough' according to animal scientist Ermias Kebreab, but eliminating targeted ciliates from cattle would require isolation and sterilized conditions, as noted by microbiologist Todd Callaway. Agriculture with ruminant animals accounts for about 30% of human-caused methane emissions.
Key facts
- A newly discovered cell structure called the hydrogenobody in rumen ciliates may explain high methane emissions from cows.
- The study was published in the journal Science on April 30.
- Researchers created a catalogue of genomes for 450 ciliates from cattle, sheep, goats, and deer.
- They identified 65 ciliate species, 45 of which had never had their genomes examined.
- In 100 dairy cows, more ciliates correlated with more methane-producing microbes and higher emissions.
- In sheep, high-methane emitters had up to 100 times more Dasytricha ciliates than low emitters.
- Dasytricha cells contain about 28 times more hydrogenobodies than the genus Entodinium.
- Hydrogenobodies have one membrane, unlike the two-membrane hydrogenosome, suggesting different evolutionary origins.
- Ermias Kebreab called the findings a 'mechanistic breakthrough'.
- Todd Callaway noted that eliminating targeted ciliates would require isolation and sterilized food.
- Agriculture with ruminant animals accounts for about 30% of human-caused methane emissions.
- Methane is 28 times more potent than carbon dioxide and a single cow can burp 220 pounds per year.
Entities
Institutions
- Chinese Academy of Sciences
- University of California, Davis
- University of Georgia
- Science
- Nature
- Scientific American
- Science News
Locations
- New York City