Faeces from baby kangaroos helped slash the amount of methane produced by bacteria in an artificial cow stomach.
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| Cows produce a large portion of global methane emissions Shutterstock/Volodymyr TVERDOKHLIB |
Kangaroo faeces may be able to help reduce the amount of methane produced by cows – a significant contributor to greenhouse gas emissions from farming.
Methane has a warming effect in the atmosphere that is almost 30 times more potent than that of carbon dioxide. Around half of global methane emissions come from ruminants like cattle and goats, which harbour a group of bacteria called methanogens in their stomachs. Methanogens scavenge and consume hydrogen gas – produced during the digestion of sugars – and use it to produce methane, which is then released from the animal’s body.
Previously, researchers have tried various feed additives for reducing methanogens in ruminants, such as antibiotics and plant extracts, as well as the development of vaccines. However, the methanogens were either simply too robust to be replaced or relying solely on antibiotics upset the entire rumen ecosystem. That is why “we wanted to look for alternative systems that are already efficient in nature”, says Birgitte K. Ahring at Washington State University.
For that, Ahring and her colleagues turned to baby kangaroos, which have bacteria in their gut that use hydrogen and carbon dioxide to produce acetic acid instead of methane.
The researchers collected droppings from baby kangaroos from petting zoos outside Seattle, and grew the microorganisms present in them in the lab to create a stable community of microorganisms. They then placed the faecal culture in a bioreactor designed to mimic the stomach of a cow. It contained a similar mixture of nutrients as a cow’s stomach, as well as some actual stomach fluid to recreate the gut microbiome.
The team found that the use of baby kangaroo faeces alone didn’t result in reduction of methanogens. However, using a chemical that inhibits methanogen first allowed the acetic acid-producing bacteria to outcompete the methanogens. Over a 12-day test period, the artificial rumen didn’t produce any methane.
While the results are promising, “a lot of solutions that have worked well in pure culture or controlled environments may not work at all when applied to animals”, says Eric Altermann at Massey University in New Zealand.
Ahring is planning to next investigate the practicality of faecal microbiota transplants with live animals.
Journal reference