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Crustacean key to breaking down lignin for biofuels

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According to the University of York, scientists who have been studying the digestive system of a wood-eating crustacean have recently discovered that it may have the answer to sustainably converting wood into biofuel.

Small marine invertebrates, Gribble have evolved to perform an important ecological role eating the large amount of wood that has been washed into the sea from river estuaries. Until now, the way Gribble break through lignin has been unknown. The sea creatures are remarkably able to find a way through the extremely resistant coating that wraps around the sugar polymers that compose wood.  

Led by the University of York, a team of scientists have studied the hind gut of gribble and discovered that hemocyanins are vital to how the crustaceans extract sugars from wood. hemocyanins are also the same proteins that make the blood of invertebrates blue. The discovered proteins are part of a group that are better known for their role in transporting oxygen in invertebrates in a similar way to haemoglobin in animals.

Gribbles appear to have harnessed the oxidative capabilities of hemocyanins to break the lignin bonds that bind the wood together. The scientists explain that this is because oxygen is highly reactive.

This recent discovery has meant that researchers are even closer to being able to identify a cheaper and more sustainable way to convert wood into low carbon fuel. This would make for a promising alternative to fossil such as coal and oil.

The research was carried out by teams from the Universities of York, Portsmouth, Cambridge and Sao Paulo. It concluded that treating wood with hemocyanins enables almost double the amount of sugar to be released, whilst more expensive and energy consuming thermochemical pre-treatments release exactly the same amount.  

The University of York’s Professor Simon McQueen-Mason from the Department of Biology and leader of the research team said that, “Gribble are the only animal known to have a sterile digestive system. This makes their method for wood digestion easier to study than that of other wood-consuming creatures such as termites, which rely on thousands of gut microbes to do the digestion for them.”

He added, “We have found that Gribble chew wood into very small pieces before using hemocyanins to disrupt the structure of lignin. GH7 enzymes, the same group of enzymes used by fungi to decompose wood, are then able to break through and release sugars.”