Ready to combat plastic debris is the T-shirt chewing enzyme.

By Maggie On Nov 28, 2023

Sintawee Sulaiman, a researcher, commenced her initial laboratory position at the University of Osaka in Japan in 2010. Ready to combat plastic debris is the T-shirt chewing enzyme. Leaf-branch compost cutinase, an enzyme discovered by her colleagues in a pile of decomposing leaves in the park adjacent to the university, was the subject of her alterations and experiments.

Ms. Sulaiman anticipated that LCC, which aids microbes in decomposing the waxy coating of leaves, could also aid in the degradation of plastic.

She shattered the plastic packaging of a pair of headphones one afternoon and submerged the fragments in water overnight along with some LCC samples. It appeared differently by morning.

“The piece of plastic had some holes, or some breakdown,” according to her. “That made me feel so surprised.”

PET, the plastic, was a polymer composed of monomers, which are smaller chemical units firmly interconnected to form a long molecule.

An instance of a ubiquitous polymer in nature is cellulose, which serves as a structural element in trees and various other plant species.

In order to degrade organic matter, microorganisms have developed enzymes that facilitate the breakdown of their chemical bonds.

However, enzymes have only been in contact with plastics for a few decades, which explains why the substances have yet to degrade. Nevertheless, scientists have discovered a way to assist evolution over the last twenty years.

Professor Alain Marty and his associates at the University of Toulouse in France have been engaged in this endeavor.

Over the course of eight years, LCC was redesigned as LCCICCG, a certified PET specialist.

At this point, the enzyme has achieved such high efficiency that it can completely decompose the PET polymer into its elemental monomers, which are the compounds required to manufacture new plastic. It is comparable to Prof. Marty disassembling a pearl necklace.

“We are using an enzyme that you can consider a molecular scissors,” he continues. “We break down the link between the pearls, liberate the pearls and in this way, after purification, we can sell these pearls again.”

Presently, he holds the position of chief scientific officer at Carbios, a company headquartered in Clermont-Ferrand, a region situated in central France.

It resembles a microbrewery in appearance, with a large cylindrical reactor surrounded by PET plastic processing equipment.

The largest machine ever constructed processes polyester-rich garments. Polyester, which is a variant of PET plastic, constitutes approximately 50% of the global apparel fiber output.

Ultimately, the majority of these garments are disposed of in landfills or incinerators, frequently in developing nations.

The large machine in Clermont-Ferrand, on the other hand, provides them with an afterlife by pulverizing them and removing buttons and sequins with precision.Following this procedure, the fabric remnants are fed into an additional machine that transforms them into soft pellets. Plastic container fragments resembling mountains of gems are processed by the identical machine, where they are also transformed into pellets. By performing this operation, the material’s surface area is expanded, and the molecular bonds of the plastic are weakened.

Notably, the granules are not required to consist entirely of PET. The textile granules comprise additional fabrics, such as cotton, while the bottles contain green dyes. Additionally, mixed plastics, including food containers, can be managed.

Operations are about to be significantly expanded by the company. The objective is to establish a facility in northeast France by 2025 that can recycle 50,000 tonnes of PET waste annually; that is equivalent to two billion bottles or 300 million T-shirts.

Carbios does not intend to engage in recycling; rather, it intends to license its process to other businesses, thereby facilitating its rapid dissemination. A consortium consisting of prominent brands such as Nestle, L’Oréal, and PepsiCo has been established.

With the production of chemical monomers that are already being utilized by plastic producers, only minor modifications are required.

However, the level of familiarity with its product also presents a difficulty, as these indistinguishable compounds will be priced approximately 60% higher than those produced from petrochemicals.

“Over time, Carbios will gain access to an increasing quantity of feedstock,” says Carbios CEO Emmanuel Ladent.

“So the cost of raw materials will go down, because we have access to feedstocks which today are incinerated or go to landfill.” Additionally, any future carbon tax will benefit them, he adds.

Other research groups, employing an assortment of enzymes, are engaged in the exploration of PET recycling, in addition to Carbios.

However, none of these organizations are currently in a position to expand their processes.