Firebrat on a branch

Biofuel production could be boosted with ancient insect enzymes

Image credit: University of York

A University of York study has opened up the possibility to use the abilities of ancient insects to boost biofuel production in the future.

The researchers made the discovery of a new class of enzymes while studying the digestive system of firebrats: a species generally considered a pest. Firebrats belong to a primitive group of insects which were first recorded on land during the Devonian Period, approximately 240 million years ago. They are generally considered pests.

Firebrats can thrive on straw, paper and cardboard, all of which contain crystallise cellulose. This forms the fibres that support cell walls and has a high degree of structural order, rendering it tough.

While studying the creatures, the team found that the insects use a particular group of proteins to digest cellulose.

“Inside their gut, the firebrats had a group of uncharacterised proteins that make up 20 per cent of their carbohydrate digestive enzymes,” said Dr Federico Sabbadin of York’s Department of Biology. “On further inspection, these proteins proved to be a new class of enzyme, called lytic polysaccharide monooxygenases (LPMOs), which attack crystalline polysaccharides.”

“Our study revealed that these enzymes are used by firebrats to greatly increase the rate of cellulose digestion.”

Before now, it was assumed that LPMOs only occurred naturally in simpler organisms: fungi, bacteria and viruses. This study demonstrates that it is, in fact, widespread among invertebrates. The researchers believe that these enzymes may have evolved from enzymes which digest chitin, a fibrous substance which constitutes most of an insect’s exoskeleton.

“We found that these ancestral genes are essential for metamorphosis and that interfering with their function is lethal to insects,” said Professor Simon McQueen Mason, chair in materials biology. “This could have important implications for the development of new methods to control disease-carrying mosquitos and agricultural pests such as locusts.”

This approach to breaking down cellulose could also be exploited on an industrial scale in sustainable development. The 2015 Paris Agreement – to which almost every UN state is a signatory – requires that governments find ways to cut carbon emissions in order to mitigate climate change and its most devastating impacts. An important aspect of this will be the move towards cleaner energy sources.

According to the researchers, these enzymes could be used to break down cellulose in biomass into fermentable sugars to boost the production of renewable, low-carbon biofuels.

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