Plastics : Cow bacteria-An untapped solution to our plastic waste problem?

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Austrian researchers have discovered that microbes originating in a cow’s stomach can help break down select polymers.

Hailing from the University of Natural Resources and Life Sciences in Vienna, Dr. Doris Ribitisch and her team were inspired by the fact that cows are able to digest certain natural plant polyesters. Bacteria endemic to a bovine rumen-that is, the largest stomach chamber of a cow-are what helps the animal to break down tough plant matter. The research team set out to find whether the same microbes would serve to degrade manmade plastics as well.

They examined three types of plastic which are as follows: polyethylene terephthalate, more commonly known as PET is commonly used in textiles and packaging (the ubiquitous PET-bottles!), polybutylene adipate terephthalate (PBAT), a biodegradable plastic used to make compostable shopping bags as well as polyethylene furanoate, (PEF), often used to make bottles, films and food trays.

First off, the scientists acquired rumen liquid from an Austrian slaughterhouse to source the needed micro-organisms. Then, they immersed all three plastics (in liquid as well as powder form) within said liquid to judge the effectiveness of the degradation process.

The study, published in the journal Frontiers in Bioengineering and Biotechnology, proved the research team’s hypothesis, namely that cow microbes can break down plastics, with those in powder form degrading most easily. The team attributed its satisfactory results to the fact that it chose to study the microbial community living within the rumen liquid rather than a particular enzyme, the conclusion being that a mix of enzymes rather than a single enzyme are the ultimate game-changer when it comes to effective plastic degradation.

DNA analysed from the rumen liquid sample identified 98 percent of the microbes involved in the degradation process with bacteria. Genetically engineering those bacteria to assist in the recycling process would be the next step.

“Due to the large amount of rumen that accumulates every day in slaughterhouses, upscaling would be easy to imagine”, is Dr. Ribitsch personal take on a potentially universal application of her team’s scientific discovery. She adds, however, that as of yet, wide-scale application of microbial solutions to plastic packaging remain challenging so long as the cost for lab equipment remains prohibitive and the need for pre-studies on micro-organisms persists.

As a biological means of recycling plastic, using fungi and bacteria proves a uniquely green solution to the plastic waste crisis. Other waste management measures such as incineration contribute to air pollution while the environmental impact of chemical recycling, which also entails the release of toxic chemicals into the air, similarly can’t be underestimated.