In the fight against waste, bacteria and fungi that are able to break down plastic molecules can play a key role. An international team of scientists recently identified new strains of plastic-eating bacteria and fungi in Chinese coastal salt marshes. The findings could open new possibilities for global waste management, according to a study published in the Journal of Hazardous Materials. [1]
“A total of 184 fungal and 55 bacterial strains capable of breaking down,” various plastics were found in the Jiangsu province of eastern China, the Royal Botanic Gardens in Kew said in a statement. Researchers from China and the UK in May 2021 sampled microorganisms from China’s Dafeng, a UNESCO-protected site near the coast of the Yellow Sea.
“Terrestrial plastisphere”
Researchers said they found a distinct “terrestrial plastisphere“, described as a “man-made ecological niche“, which is an ecosystem that has evolved to live with the presence of coastal plastic debris.
Because of their longevity and hydrophobic surface, plastics in aquatic ecosystems have the potential to create a sort of ‘microbial reef’ for fungi and bacteria to attach to. And certain plastics can provide microbes with a source of carbon to metabolize – a food source.
At Dafeng, the researchers collected 50 samples of plastic waste from seven different types of petroleum-based polymers: polyethylene terephthalate (PET), expanded polystyrene (EPS), polyethylene (PE), polyurethane (PU), polyamide (PA), polypropylene (PP), and polyvinyl chloride (PVC).
Among the samples, the researchers identified 14 genera of fungi, including the plant pathogens Fusarium and Neocosmospora. The study’s findings indicate these fungi may be better at degrading polycaprolactone (PCL) plastics and other synthetic polymers than saprotrophic fungi.
An innovative way to recycle plastic
“Scientists are increasingly looking at microorganisms, such as fungi and bacteria, to help tackle some of the most pressing challenges of the modern age, including the rising tide of plastic pollution,” Kew Gardens said.
In the wild, fungi play a key role in breaking down organic matter. Over millions of years, their ability to break down many complex and naturally occurring polymers, such as cellulose, has made them able to produce enzymes that are extremely efficient at breaking down complex organic compounds.
The new findings contribute to existing studies on plastic-degrading microorganisms with some 436 species of fungi and bacteria found capable of breaking down plastic to date. RGB Kew scientists believe their latest findings could lead to the development of efficient enzymes designed to biologically degrade plastic waste.
Enzymatic recycling
French start-up Carbios has pioneered the enzymatic recycling of plastic, more specifically PET. Thanks to their demonstration unit in Clermont-Ferrand, they have demonstrated the technical feasibility of using enzymes in an energy-efficient recycling process, paving the way for the construction of a first commercial plant whose commissioning is scheduled for 2025. In 2021, Carbios and L’Oréal unveiled the first plastic bottles made using enzymatic recycling technology.
Carbios recently accelerated its micro-organism screening process with a microfluidic technology developed in partnership with the Paul Pascal Research Centre (a joint research unit of the CNRS and the University of Bordeaux, France) in order to reduce the time required to develop and produce new enzymes capable of breaking down different types of plastic polymers. The discovery of new plastic-eating strains should contribute to feed this research!
