Wood-eating gribble could be key to biofuel future
Studying the gribble, a tiny marine organism that eats wood, has revealed a surprising discovery that may be an important step in the quest for sustainable fuels.
Using advanced biochemical analysis and X-ray imaging techniques at Diamond Light Source, researchers from 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 in the gribble’s stomach that enables it to break down wood.
“Gribbles used to be the scourge of the navy,” Dr John McGeehan, a structural biologists from the University of Portsmouth team, told Laboratory News. “The creatures historically attacked the timber hulls of seafarer’s ships and continue to destroy seaside piers like the ones in Portsmouth.”
It has been known for a long time that gribbles are ferocious gobblers of wood, but it was previously assumed that microbes in their gut provided the enzymes needed to perform this task. However, the researchers discovered to their surprise that the gribble possesses a sterile stomach which means it uses its own enzymes to break the polysaccharides in wood into simple sugars.
“Similar enzymes have been found in wood-degrading fungi, but this is totally new. It’s the first cellulase that’s ever been found in an animal,” said McGeehan.
The team transferred the genetic blueprint of the gribble’s cellulase to an industrial microbe that could produce it in large quantities. They were then able to make crystals of the enzyme and transport them to Diamond Light Source, the UK’s National Synchrotron Science Facility.
There, the researchers fired an intense beam of X-rays at the crystals to generate a series of images that can be transformed into 3D models. The team at the National Renewable Energy Laboratory then used powerful supercomputers to model the enzyme in action to reveal how the cellulose chains of wood are digested into glucose.
“Looking at the enzyme’s 3D shape revealed some unexpected results,” said McGeehan. “The enzyme skeleton looks very similar to cellulases found in fungi, but its surface is completely different. We think this is because the enzyme evolved in sea water and can therefore survive very harsh conditions (high salt concentrations). This means the enzyme has real biotech applications.”
The ultimate aim is to reproduce the effect of the gribble’s enzyme on an industrial scale in a bid to create sustainable liquid biofuels.
“The biotech industry needs to copy what nature has already done and I think this is quite a timely discovery considering the country’s rising energy bills. A real focus is needed on producing sustainable energy and this little gribble could be a game changer,” said McGeehan.
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