Microbes capable of digesting plastics at low temperatures discovered

By Al Mayadeen English
Source: Agencies
10 May 2023 09:56

The microbes have been discovered by scientists in the Alps and the Arctic.

Plastic bottles ready for processing sit at a recycling center. (AP)

Scientists have discovered microbes in the Alps and the Arctic that are capable of digesting plastics at low temperatures, which could be a useful tool in recycling.

There are already a lot of bacteria that can accomplish this, but they typically only function at temperatures higher than 30°C (86F). This means that because heating them up is necessary, using them in industrial applications is unaffordable. Utilizing them also means that it is not carbon neutral.

Researchers at the Swiss Federal Institute WSL have discovered bacteria that can perform this function at 15°C, which may mark a significant advance in the field of microbial recycling. Their findings have been published in the journal Frontiers in Microbiology.

In Greenland, Svalbard, and Switzerland, Dr. Joel Rüthi of WSL and colleagues collected samples of 19 bacterial strains and 15 fungal strains that were growing on free-lying or purposefully buried plastic that had been left in the ground for a year. They studied the microorganisms to determine if they could digest various kinds of plastic and let them grow as single-strain cultures in the laboratory under darkness at 15°C.

The findings revealed that the bacterial strains belonged to 10 genera in the phyla ascomycota and mucoromycota and the fungi to 13 genera in the phyla actinobacteria and proteobacteria.

The plastics put to the test were two commercially available biodegradable blends of polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA), non-biodegradable polyethylene (PE), and biodegradable polyester-polyurethane (PUR).

The global production of #plastic is measured in millions of metric tons. The majority of the plastic #garbage that is left over eventually finds its way into our oceans, even if half of it is recycled, burned, or dumped in landfills. pic.twitter.com/i90dQKqJ9B
— Al Mayadeen English (@MayadeenEnglish) March 18, 2023

Despite being incubated on these plastics for 126 days, none of the strains could digest PE. However, PUR could be broken down by 19 strains (56%), comprising 11 fungus and 8 bacteria, at 15 degrees Celsius, while PBAT and PLA plastic mixes could be broken down by 14 fungi and 3 bacteria.

Rüthi said, “Here we show that novel microbial taxon 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.”

The highest performers were discovered after additional testing to be two unidentified fungus species belonging to the genera Neodevriesia and Lachnellula, which could break down all of the tested polymers with the exception of PE.

Although plastics have only been widely used since the 1950s, bacteria can break down polymers because they resemble some plant cell structures.