Waste: plastic-eating fungi and bacteria that could save the world

The aim of the project was to evaluate a number of fungal strains for use in bio-isolation panels, but the hungry fungi took it in another direction.

Biome is currently working on developing a strain of the fungus to make it a more efficient digestive tool that could help get rid of plastic waste.

It’s no secret that single-use plastic waste is a huge problem. In 2015, according to Greenpeace, the world produced 6.3 billion tonnes of plastic, of which only 9% was recycled, and the rest was burned in incinerators or dumped in special waste. landfills.

But things are looking up, with more than 40 percent of plastic packaging now recycled in the European Union, and looking to increase that figure to 50 percent by 2025.

But some plastics, like PET (polyethylene terephthalate), widely used to make beverage bottles, are difficult to recycle by conventional means. Could organic methods be the solution?

Jenkins tests his fungus on PAT plastics and on polyurethane, which is used to make materials such as paint and adhesives.

“Mushrooms eat plastic, they make more fungi, and then you can make biomaterials… for food, feed, or antibiotics.”

Other scientists have also had some success in this area.

Scientists at the University of Edinburgh recently used a lab-modified version of E. coli bacteria to convert terephthalic acid, a molecule derived from PET, into the flavor of cooking vanilla, through a series of chemical reactions.

“Our study is still at a very early stage and we need to do more to find ways to make the process more efficient and economically viable,” says Dr Joanna Sadler, of the university’s School of Biological Sciences.

“But this is a really exciting place to start, and it is possible that it will be a viable solution in the future after further improvements to the process,” she continues.

Meanwhile, a team from the Helmholtz Center for Environmental Research in Leipzig, Germany, are using a bacteria called Pseudomonas that originated from a local landfill to break down polyurethane waste.

In the process, bacteria consume about half of the plastic to increase their biomass, with the rest being released as carbon dioxide.

Like other organisms that feed on plastic, Pseudomonas bacteria break down polyurethane with the help of enzymes. The team has now performed a genetic analysis of the bacteria with the aim of identifying specific genes that code for these enzymes.

But some wonder if these technologies are commercially viable.

Professor Ramani Narayan, Michigan State University, says: “Converting enzymes or microbes into building blocks of the BIT is an interesting science and should be explored. But the technology should compete with proven commercial conversion techniques using Standard aqueous catalyst systems. “.

Karbius, a French company that uses a modified version of an enzyme originally found in a compost heap to break down PET, has perhaps gone the greater route of commercialization.

After collaborating with some of the big names in consumer products, including L’Oréal and Nestlé, the company recently announced that it has produced the world’s first PET bottles, made entirely from enzymatically recycled plastic.

And unlike most recycling methods, enzymes can process colored PET plastic.

“With traditional methods such as mechanical recycling to make the end product suitable for transparent plastic bottles, you need transparent bottles to start,” said Executive Vice President Martin Stefan.

He continues: “As for the technology we use, it can process and recycle any type of PET plastic. “

However, vials produced by this process cost twice as much as those using petrochemicals.

Despite this, Stefan says, this technology has the potential to match the lower costs of traditionally manufactured vials.

Dr Wolfgang Zimmermann of the Institute for Analytical Chemistry at the University of Leipzig in Germany considers the Karbius technique to be promising.

“Enzymes can be very useful because they are very specific and they don’t care if the packaging is still dirty. And they don’t take a lot of energy.”

“The other thing is that they can be easily scaled up and down. Enzymes have the advantage that they can be made into small units with a low carbon footprint and can be used outside urban areas in developing countries or in remote locations, ”he adds.

However, he does not see it as a panacea.

“PET vials using this enzyme can be recycled into new vials, but unfortunately PET vials are very crystalline and very resistant to the enzyme inactivation process. The company therefore had to introduce an additional pretreatment in which it put a lot of additional energy to dissolve the substance to reduce crystallization.

“Then you can break it down with the enzyme – but economically, as well as in terms of the carbon footprint, that’s not very feasible in my opinion.”

And while things might get better, enzyme recycling is currently very limited, admits Stephan.

“We have developed technologies to process just two types of polyester, which represent around 75 million tonnes of annual production, against a global plastic production of around 350 million tonnes,” he says.

He concludes: “We have a lot of work ahead of us.