Baby kangaroo poo could combat methane from cows and aid muscle growth

Baby kangaroo poo may serve as a novel solution to the environmental issue of cow-produced methane, according to a news release published on February 14. 

Scientists were able to demonstrate that a microbial culture created from kangaroo feces could inhibit the production of methane which cows discard as flatulence (otherwise known as back passage gas or farts). Better yet, the inhibitor created a by-product that aids cows' muscle growth.

How can baby kangaroo poo reduce methane emissions?

Washington State University (WSU) researchers, who study fermentation and anaerobic processes, simulated cow digestion using an artificial rumen they had previously designed. A rumen is the largest stomach compartment found in ruminant animals.

Rumens have "amazing abilities," said Ahring, a professor at the Gene and Linda Voiland School of Chemical Engineering and Bioengineering and in Biological System Engineering. Rumens have several enzymes that can break down natural materials.

Her team discovered that baby kangaroos – and not adults – had bacteria in their foreguts that produce acetic acid, which aids muscle growth, rather than methane.

They chose a stable mixed culture created from a baby kangaroo's feces as they could not identify the precise bacteria that might be responsible for creating the acetic acid.

After initially reducing the methane-producing bacteria in their reactor with a specialized chemical, the acetic acid bacteria were able to replace the methane-producing microbes.

"It is a very good culture. I have no doubt it is promising," Ahring said. "It could be really interesting to see if that culture could run for an extended period of time, so we would only have to inhibit the methane production from time to time." In this way, the researchers hope to try it on real cows sometime in the future.

Why do we need to make 'cow gas' methane-free?

Methane is the second-largest greenhouse gas contributor and has a heating effect on the atmosphere that is nearly 30 times greater than that of carbon dioxide. 

Ruminant animals, such as cattle and goats, are estimated to contribute most of the methane released into the atmosphere from the agricultural industry. Furthermore, 10 percent of the animal's energy is required to produce methane.

Researchers worldwide have tried feeding cows different diets and chemical inhibitors to limit the creation of methane. Still, the methane-producing bacteria quickly develop resistance to the medications. 

Some have also attempted to create vaccines. However, the microbiome of a cow depends on the food it consumes, and there are far too many different types of methane-producing bacteria in the world. The biological functions of the animals may also be affected by the interventions.

The full study was published in the journal Biocatalysis and Agricultural Biotechnology.

Study abstract:

Methane from anaerobic fermentation in the rumen of cattle is a major contributor to greenhouse gases (50–60%). Methanogenesis is an important process in the ruminants as it scavenges hydrogen produced during the anaerobic fermentation of sugars in the rumen and, thereby, balances the fermentation process. This work focuses on mitigation of methane production in rumen by bioaugmentation with hydrogenotrophic acetogenic strains thus, channelizing hydrogen towards acetate instead of methane. For this two acetogenic cultures: Acetobacterium woodii and a stable consortium from a baby kangaroo feces sample were used as potential competitors for hydrogen-carbon dioxide against rumen methanogens. Addition of Acetobacterium woodii or an acetogenic kangaroo consortium had only limited effect on methane production from continuously grown rumen cultures. However, one-time treatment with an inhibitor of methanogenesis (2-bromoethanesulfonic acid), along with addition of either of the two acetogenic cultures resulted in well-functioning fermentation process with acetogenesis with no methane production. Monod's growth kinetics studies were done to test the ability of selected homoacetogens to compete against methanogens for hydrogen. The results show a lower Ks value for the methanogenic culture (0.737 mM hydrogen) compared to the Ks values for Acetobacterium woodii and the kangaroo consortia of 6.844 mM and 3.788 mM hydrogen, respectively. The Vmax was found to be similar for the methanogenic and kangaroo culture (0.381 mM/h and 0.331 mM/h, respectively) but lower for Acetobacterium woodii (0.217 mM/h).