“Molecular scissors” for plastic waste

A research team from the University of Greifswald and Helmholtz-Zentrum-Berlin (HZB) has solved the molecular structure of the important enzyme MHETase at BESSY II.

MHETase was discovered in bacteria and together with a second enzyme – PETase – is able to break down the widely used plastic PET into its basic building blocks. This 3D structure already allowed the researchers to produce a MHETase variant with optimized activity in order to use it, together with PETase, for a sustainable recycling of PET. The results have been published in the research journal Nature Communications.

Plastics are excellent materials: extremely versatile and almost eternally durable. But this is also exactly the problem, because after only about 100 years of producing plastics, plastic particles are now found everywhere – in groundwater, in the oceans, in the air, and in the food chain. Around 50 million tonnes of the industrially important polymer PET are produced every year. Just a tiny fraction of plastics is currently recycled at all by expensive and energy-consuming processes which yield either downgraded products or depend in turn on adding ‘fresh’ crude oil.

>Read more on the BESSY II at HZB website

Image: At the MX-Beamlines at BESSY II, Gottfried Palm, Gert Weber and Manfred Weiss could solve the 3D structure of MHETase.
Credit: F. K./HZB

Analysing the structure of biopolymers for the food industry

A research group from the Institute of Agrochemistry and Food Technology (IATA-CSIC) in Valencia is using scattering techniques at the ALBA Synchrotron to develop new packaging systems made of biopolymers, an environmentally friendly solution for the food industry.

Plastic is the packaging material of most of the food we consume nowadays. This results in a severe problem as common plastics are made of petroleum – a limited resource with highly variable price – and supposes a huge environmental impact – most plastic wastes need more than 400 years to decompose.

Researchers from the Food Safety and Preservation department of the Institute of Agrochemistry and Food Technology (IATA-CSIC), located in Paterna (Valencia), are looking for more sustainable ways of producing food packaging with appropriate mechanical and chemical properties. They are investigating biopolymers that can be made from biomass such as algae.
“We need to look for alternative sources which do not compete with food. This is why marine resources such as algae and microalgae are very interesting. They proliferate very quickly, grow in a wide variety of environments and do not interfere with food production”, according to Ámparo López-Rubio, researcher at the IATA-CSIC.

>Read more on the ALBA website

Image: At the left, Juan Carlos Martínez, scientist from the ALBA Synchrotron with users Amparo López Rubio and Marta Martínez Sanz from IATA-CSIC at the NCD-SWEET experimental hutch.

Solution to plastic pollution on the horizon

Engineering a unique plastic-degrading enzyme

The inner workings of a recently discovered bacterium with a fascinating ability to use plastic as an energy source have been recently revealed in PNAS. The world’s unique Long-Wavelength Macromolecular Crystallography (MX) beamline here at Diamond Light Source was used to successfully solve the structure of the bacterial enzyme responsible for chopping up the plastic. This newly evolved enzyme could be the key to tackling the worldwide problem of plastic waste.

Plastic pollution is a global threat that desperately needs addressing. Plastics are rarely biodegradable and they can remain in the environment for centuries. One of the most abundant plastics that contributes hugely to this dire situation is poly(ethylene terephthalate) (PET).

PET is used largely in textiles, where it is commonly referred to as polyester, but it is also used as packaging for liquids and foodstuffs. In fact, PET’s excellent water-repellent properties led to it being the plastic of choice for soft drink bottles. However, once plastic bottles are discarded in the environment the water resistance of PET means that they are highly resistant to natural biodegradation. PET bottles can linger for hundreds of years and plastic waste like this will accumulate over time unless a solution is found to degrade them.

A recent breakthrough came in the discovery of a unique bacterium, Ideonella sakaiensis 201-F6, which was found feeding on waste from an industrial PET recycling facility. PET has only been widely used since the 1970s, so the bacterium had evolved at breakneck speed to be able to take advantage of the new food source.

The bacterium had the amazing ability to degrade PET and use it to provide carbon for energy. Central to this ability was the production of a PET-digesting enzyme, known as PETase.

>Read more on the Diamond Light Source website