Discovery of a New Class of Enzymes to Convert Plant Waste into Eco-friendly Products

A cross-institutional team of scientists has engineered a new family of enzymes to convert plant waste into sustainable and high-value products, such as nylon, plastics and chemicals.

Lignin – A Main Component of New Enzymes

The newly engineered enzyme is active on lignin – one of the main components of plants, which scientists have been trying for decades to find a way of breaking down efficiently. Lignin acts as scaffolding in plants and is central to water-delivery. It provides strength and defence against pathogens.

Professor McGeehan, Director of the Centre for Enzyme Innovation in the School of Biological Sciences at Portsmouth said, “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.”

“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,” he further added.

Engineering of Naturally Occurring Enzymes

The team’s goal is to discover enzymes from nature, bring them into our laboratories to understand how they work, then engineer them to produce new tools for the biotechnology industry. In this case, the team has taken a naturally occurring enzyme and engineered it to perform a key reaction in the breakdown of one of the toughest natural plant polymers.

Current enzymes tend to work on only one of the building blocks of lignin, making the breakdown process inefficient. Using advanced 3D structural and biochemical techniques the team has been able to alter the shape of the enzyme to accommodate multiple building blocks. The results provide a route to making new materials and chemicals such as nylon, bioplastics, and even carbon fiber, 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, helping to reduce CO2 emissions.

An International Research Team of Specialized Experts

The research team was made up of an international team of experts in structural biology, biochemistry, quantum chemistry and synthetic biology at the Universities of Portsmouth, Montana State, Georgia, Kentucky and California, and two US national laboratories, NREL and Oak Ridge.

Professor McGeehan said, “We now have proof-of-principle that we can successfully engineer this class of enzymes to tackle some of the most challenging lignin-based molecules and we will continue to develop biological tools that can convert waste into valuable and sustainable materials.”

The research was jointly funded by the Biotechnology and Biological Sciences Research Council (BBSRC), National Science Foundation (NSF), and the DOE EERE Bioenergy Technologies Office. The 3D enzyme structures that underpinned this work were solved at the Diamond Light Source, the UK’s national synchrotron science facility in Oxford. 

Source: UoP News