A cow farts in a feedlot isn’t just a roadside view in the Midwest: for climatologists, it’s a cause for concern. After all, cow farts and burps release significant amounts of methane into the atmosphere. Beef production currently represents 3.7% of greenhouse gas emissions in the USA
But while cows can slowly kill the planet – death by millions of farts, if you will – new research indicates that the digestive tract of cattle may have the ingredients to save us.
According to research published Friday in the newspaper Frontiers in bioengineering and biotechnology, The microbes that break down food in the intestines of cows could help solve the massive plastic problem engulfing planet Earth.
“A huge microbial community lives in the rumen reticulum and is responsible for the digestion of food in animals”, Doris Ribitsch, co-author of the study of the University of Natural Resources and Life Sciences Vienna mentionned in a press release.
What’s up – Cow guts, like ours, are teeming with microbes like bacteria, fungi and other microbes. These intestinal flora contain enzymes that can break down and digest food.
In a particularly large chamber of the cow’s stomach, known as the rumen, the bacteria digest the plant cellulose in the grass and the food that the cow eats.
Researchers believe that because the cow’s intestine breaks down natural plant polyesters, rumen flora could likely do the same for polyesters found in plastics.
The team thus tested the extent to which cow rumen could degrade or break down three common polyester materials found in plastic:
- Polyethylene terephthalate (PET) – A lightweight plastic found in many ccommon types of packagingincluding water bottles
- Polybutylene adipate-co-terephthalate (PBAT) – A biodegradable plastic that has been used in compostable packaging
- Polyethylene furanoate (PEF) – A plastic made of renewable materials which serves as an alternative to PET for bottled beverages and packaging
It turns out that the cow rumen and its arsenal of bacteria are very effective at breaking down plastic in a sustainable way. The researchers write that the “rumen samples succeeded in degrading the three polyesters tested”.
However, rumen microbes were more active when it came to digesting PEF than PET. PET is notoriously hard to fail. PET can be found in common items like plastic water bottles, which often degrade into microplastics.
How they did it – From a cattle slaughterhouse in Austria, researchers received a liquid suspension of rumen microbes. The scientists then incubated the liquid with one form of each of the plastics – either plastic powder or plastic wrap.
This method allowed researchers to see how the chemistry of the rumen breaks down each of the plastics.
Finally, the researchers sequenced and analyzed the DNA of the liquid to understand the specific microorganisms that make up the flora in the rumen of cows. About 98% of the microbes were bacteria, with the rest being other microorganisms like archaea and viruses.
Why is this important – Researchers are not the first to suggest using microbes to break down waste in an environmentally friendly way. In fact, the ancient Romans used a form of bio-leaching, which scientists have proposed to recycle metals from electronic waste using bacteria.
“It shows that the mechanism of plastic digestion is more [wide]spread than we thought ”, Sebastien farnaud, professor of bio-innovation and business at Coventry University who has written on bio-leaching and did not participate in the study, says Reverse.
According to a 2017 report from the American Association of Science, humans have generated 9.1 billion tonnes of plastic since the 1950s. Only 9% of this plastic has been successfully recycled, and much of the rest is thrown away. in landfills, where it persists for decades, if not centuries.
Worse yet, it can break down into smaller microplastics and end up in the ocean, where it suffocates. Marine life.
Chemicals from cow rumen may be a good way to sustainably and efficiently recycle plastic in a way that does not contribute to greenhouse gas emissions, researchers suggest, because it is available in large quantities at slaughterhouses. of the whole world.
Scientists conclude that rumen fluid is a “cheap source” of bacterial plastic-degrading enzymes.
And after – Farnaud adds that this study, “gives us hope to find other enzymes – this is what these microbes secrete – [that] may be even more effective ”than those found in cow rumen.
The researchers write that “future studies should aim to identify and cultivate the microbes and enzymes” that can break down plastic.
However, Farnaud says the lack of scientific research or technology isn’t the biggest issue with implementing environmentally friendly microbial recycling. The challenge lies in another factor: the lack of investment in eco-recycling.
“The main problem is not technical. It’s economical, ”says Farnaud. “There is no money in plastic recycling, so this investment to develop these technologies [is] very difficult to find.
However, Farnaud suggests that biotechnology could help make these plastic-degrading enzymes more commercially attractive. In 2018, scientists at the University of Portsmouth reported enzymes which can break down plastic found in water bottles, paving the way for such industrial use.
With the help of the enzymes that inhabit our mooing friends and bioengineering labs, perhaps we can save the planet from drowning in plastic trash.
Abstract: Microorganisms, such as bacteria and fungi, are becoming an emerging resource for the development of eco-sustainable plastic degradation and recycling processes. In this study, the content of the rumen of cattle (Bos taurus) was investigated with regard to hydrolysis enzymes of synthetic polyesters on the basis that the diet of ruminants may contain natural plant polyesters. Screening with model substrates demonstrated the hydrolytic activities of rumen fluid on p-NP-esters with 4 to 8 carbon atoms. Synthetic aromatic polyesters hydrolyzed in rumen fluid containing higher amounts of terephthalic acid released by poly (butylene adipate-co-terephthalate) (PBAT) (0.75 and 0.5 mM for powder and polymer film, respectively ) and thus exceeded with respect to the hydrolysis of the second polymeric terephthalic acid-poly (ethylene terephthalate) (PET) base (0.6 and 0.15 mM, for the powder and the film, vice versa). , rumen fluid hydrolyzed biobased polyester poly (ethylene furanoate) (PEF) according to HPLC and SEM Environmental metagenomic analysis of the rumen microbial community revealed a composition of bacteria (98%), followed by Eukaryota (1 %) and finally of Archaea.Among the most abundant genera encountered in this study, the hydrolysis activity of polyester has already been proven (eg pseudomonas).