Scientists create 'promiscuous' enzyme that turns plant waste into sustainable products
Scientists have created a new family of enzymes which break down plant waste into high-grade, high-value materials that can be converted into nylon, plastics and biofuels.
The breakthrough, which was made by the same team of researchers which this year created a mutant enzyme that breaks down plastic, could help drive a circular economy in numerous sectors, including textiles, packaging, technology and mobility.
Because the enzyme is classed as “promiscuous”, meaning it will work on a wide range of materials, it could also be used to break down end-of-life products, allowing companies to recycle their used items into their new designs as they move away from cradle-to-grave business models.
The international team tweaked natural enzymes to activate when they come into contact with lignin - a key component of all plants, which strengthens their structures and provides protection from pathogens. Prior to the discovery, researchers had found that only a handful of fungi species and bacteria strains could remove lignin from plant waste.
“Lignin represents a vast potential source of sustainable chemicals, so if we can find a way to extract and use those building blocks, we can create great things,” the University of Portsmouth’s professor John McGeehan, who led the research, said.
“Cellulose and lignin are among the most abundant biopolymers on earth,” he added. “The success of plants is largely due to the clever mixture of these polymers to create lignocellulose, a material that is challenging to digest.”
The team of US and UK scientists made the discovery while conducting experiments to engineer naturally-occurring enzymes, in a bid to find new ways of breaking down natural and man-made polymers, which can take centuries to degrade in nature.
Once the enzyme, known as P450, has separated the lignin from the plant waste, the created polymer can be incorporated into new materials including carbon fibre, textiles and plastics as an alternative to virgin polymers.
By creating materials and chemicals using the polymer, manufacturing firms can lower their CO2 and greenhouse gas emissions, as the process negates the need for burning oil to create resource streams.
Dr Gregg Beckham from the US Department of Energy’s National Renewable Energy Laboratory, who co-led the research, said that the promiscuity of the enzyme means it can be engineered further to target specific molecules in a bid to break down other challenging waste materials.
“We now have one of the most well-known, versatile, engineerable and evolvable classes of enzymes ready to go as a foothold for biotechnology to move forward and make the enzyme better,” he concluded.
The research comes on the heels of another study at the University of Georgia, which found a way of speeding up the evolution of the P450 enzyme. The groups are now working together to discover and evolve even faster enzymes for turning lignin into high-value sustainable products.