Scientists have discovered a new family of enzymes that could pave the way to converting plant waste into sustainable and high-value products such as fuel, nylon, plastics, chemicals.

The discovery was made by members of the same UK-US enzyme engineering team that, in April, improved a plastic-digesting enzyme, a potential breakthrough for the recycling of plastic waste.

The new enzymes can directly act on the building blocks of lignin: one of the main components of plants, which scientists have been trying for decades to break down efficiently.

"Enzymes are biological catalysts that can perform incredible reactions, breaking down some of our toughest natural and man-made polymers," said Professor McGeehan of the University of Portsmouth.

"To protect their sugar-containing cellulose, plants have evolved a fascinatingly complicated material called lignin that only a small selection of fungi and bacteria can tackle. However, 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."

Lignin acts as scaffolding in plants and is central to water-delivery. It provides strength and also defense against pathogens.

"It's an amazing material," Professor McGeehan said. "Cellulose and lignin are among the most abundant biopolymers on earth. 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 research team found a way of releasing a key bottleneck in the process of breaking down lignin to its basic chemicals. The results provide a route to making new materials and chemicals – such as nylon, bioplastics, and even carbon fibre – from what has previously been a waste product.

The discovery also offers additional environmental benefits. Creating products from lignin reduces our reliance on oil to make everyday products and offers an attractive alternative to burning it, which would help to reduce CO2 emissions.

Sam Mallinson, a student in structural biology at the university and first author on the paper, said: "There is a long-standing phrase – you can make anything out of lignin except money – but by harnessing the power of enzymes."

The enzyme is a new class of cytochrome P450, and it is promiscuous, meaning it's able to work on a wide range of molecules.

Dr Beckham said: "This new cytochrome P450 enzyme can degrade a lot of different lignin-based substrates. That's good because it means it can then be engineered to be a specialist for a specific molecule and we can evolve it further to push it in a certain direction.

"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."

The group is now working together to discover and evolve even faster enzymes for turning lignin into high-value sustainable products.

The study was published in Nature Communications.

(Source: University of Portsmouth)

Be Sure And Share The Intriguing News With Your Friends – Representative photo by jkrebs, CC