Enzyme from wood-eating gribble could help turn waste into biofuel

The 3D X-ray structure allows scientists to see inside the enzyme and reveals how it binds and digests cellulose chains. Image: John McGeehan, University of Portsmouth

Scientists have discovered a new enzyme that could prove an important step in the quest to turn waste (such as paper, scrap wood and straw) into liquid fuel.

To do this they turned to the destructive power of tiny marine wood-borers called ‘gribble’, which have been known to destroy seaside piers.

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Using advanced biochemical analysis and X-ray imaging techniques, researchers from the University of York, University of Portsmouth and the National Renewable Energy Laboratory in the USA have determined the structure and function of a key enzyme used by gribble to break down wood. The findings, published in PNAS, will help the researchers to reproduce the enzymes effects on an industrial scale in a bid to create sustainable liquid biofuels.

To create liquid fuel from woody biomass, such as wood and straw, the polysaccharides (sugar polymers) that make up the bulk of these materials have to be broken down into simple sugars. These are then fermented to produce liquid biofuels. This is a difficult process and making biofuels in this way is currently too expensive.

To find more effective and cheaper ways of converting wood to liquid fuel, scientists are studying organisms that can break down wood in hope of developing industrial processes to do the same.

Gribble are of interest as they are voracious consumers of wood and have all the enzymes needed for its digestion. The enzymes attach to a long chain of complex sugars and chop off small soluble molecules that can be easily digested or fermented. The researchers identified a cellulase (an enzyme that converts cellulose into glucose) from gribble that has some unusual properties and used the latest imaging technology to understand more about it.

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