Breakthrough in microbial recycling! Scientists discover microbes that can digest plastics at low temperatures

A valuable new tool in recycling has been found. In the latest discovery, scientists have found microbes that can break down and digest plastics at low temperatures.

Several microorganisms that can perform this have already been found, but they usually only work at temperatures above 30 degreeCelsius, which effectively means using them in the industrial sector would be expensive because of the additional heating cost, reported the Guardian.

Scientists from the Swiss Federal Institute WSL have found microbes that digest plastics at 15 degreeCelsius, which could be a scientific leap in microbial recycling. Their findings have been published in the journal Frontiers in Microbiology.

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Dr Joel Rüthi from WSL and colleagues sampled 19 strains of bacteria and 15 fungi varieties growing on free-lying or intentionally buried plastic kept in the ground for one year in Greenland, Svalbard and Switzerland, as per the Guardian.

They let the microbes grow as single-strain cultures in the laboratory in the dark at 15 degreeCelsius and tested them to determine if they could digest different types of plastic.

The results showed that the bacterial strains belonged to 13 genera in the phylum actinobacteria and proteobacteria, and the fungi to 10 genera in the phylum ascomycota and mucoromycota.

The plastics tested included non-biodegradable polyethylene (PE) and the biodegradable polyester-polyurethane (PUR) as well as two commercially available biodegradable blends of polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA).

None of the strains was able to digest PE, even after 126 days of incubation on these plastics. But 19 strains (56 per cent), including 11 fungi and eight bacteria, were able to digest PUR at 15 degreeCelsius, while 14 fungi and three bacteria were able to digest the plastic blends of PBAT and PLA.

“Here we show that novel microbial taxa obtained from the ‘plastisphere’ of alpine and arctic soils were able to break down biodegradable plastics at 15C. These organisms could help to reduce the costs and environmental burden of an enzymatic recycling process for plastic.” Dr Rüthi told the Guardian.

He said it was astonishing that a large fraction of the tested strains were able to degrade at least one of the tested plastics.

Additionally, Dr Beat Frey, one of the study authors, explained to the Guardian, “Microbes have been shown to produce a wide variety of polymer-degrading enzymes involved in the breakdown of plant cell walls. In particular, plant-pathogenic fungi are often reported to biodegrade polyesters, because of their ability to produce cutinases, which target plastic polymers due to their resemblance to the plant polymer cutin.”

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