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Bacteria from the stomach of a cow can digest some plastic, removing it from the environment, according to a team of Austrian researchers.
The polymers that plastics are made from usually aren’t digestible by ordinary organisms – be they animal, plant or bacteria – meaning the molecules accumulate in the environment very easily. While there has been some success in recent years finding microbes that can digest plastic polymers, the idea has so far been focussed on individual organisms, usually breaking down individual plastics.
This new research, published in Frontiers in Bioengineering and Biotechnology, has found a combination of bacteria from cow stomachs to be more effective at digesting three different polyesters, including the common and long-lasting polyethylene terephthalate, or PET.
The researchers, who are based at the University of Natural Resources and Life Sciences in Vienna, collected liquid from rumens (one of the four components of a cow’s stomach) from a slaughterhouse.
‘A huge microbial community lives in the rumen reticulum and is responsible for the digestion of food in the animals,’ says Doris Ribitsch, corresponding author on the study.
‘We suspected that some biological activities could also be used for polyester hydrolysis.’
Hydrolysis – using water to break down molecules – is an effective method of dealing with polymers, because it divides the long, difficult-to-digest molecules into smaller pieces. These molecules can then be easily processed further by the cow’s stomach liquid, or by other organisms in the environment, in the same way as their naturally-occurring counterparts in plants are.
The researchers incubated three different polyester plastics – PET, and two biodegradable plastics, PBAT (polybutylene adipate terephthalate) and PEF (polyethylene furanoate) – in the rumen liquid. All three of these plastics are made exclusively from carbon, hydrogen and oxygen atoms – meaning that once hydrolysed, they can ultimately become things like sugars, water, or carbon dioxide.