Marine pest 'could be the key to a biofuel breakthrough'

A wood-munching marine pest could be the key to a biofuel breakthrough, according to scientists.

Gribble, which resemble pink woodlice, plagued seafarers for centuries by boring through the planks of ships and destroying wooden piers.

But now environmental scientists are taking a keen interest in the crustaceans.

A team of Government-funded British researchers learned that gribble have a gift for digesting wood not seen in any other animal.

Enzymes produced by the tiny creatures are able to break down woody cellulose and turn it into energy-rich sugars.

This is exciting to scientists investigating green fuel sources, because it means gribble could hold the key to converting wood and straw into liquid biofuel.

A gribble-like processing plant could make sugars from woody raw material that can be fermented into alcohol-based fuels for vehicle engines.

Researchers at the universities of York and Portsmouth made the discovery after carrying out an extensive study of digestive genes from the gribble species Limnoria quadripunctata.

They found the crustacean's long digestive tract is dominated by enzymes that attack cellulose and lignin, the normally indigestible hard material in woody plant tissue.

Some of the most abundant of the proteins had never been seen before in animals.

All other animal species known that survive on tough plant fibres or wood have friendly gut bacteria which help them digest their food.

This is true of both cows and termites. But gribble have no symbiotic microbes in their digestive systems, and produce all the enzymes needed to convert wood into sugars themselves.

"This may provide clues as to how this conversion could be performed in an industrial setting," said Prof. Simon McQueen-Mason, who led the York team.

The scientists investigated a digestive organ in gribble called the hepatopancreas, a sort of appendix consisting of two blind-ended sacs connected to the stomach.

A genetic "fishing" technique was employed to identify DNA sequences and the proteins they code for. Small end pieces of DNA called "expressed sequence tags" were used to "hook out" genes by matching some of their component chemicals.

The scientists uncovered an abundance of cellulose and lignin-degrading enzymes from the glycosyl hydrolase family - a finding unique in animals.

They wrote in the journal Proceedings of the National Academy of Sciences: "This study has revealed a combination of glycosyl hydrolase genes in Limnoria that seem likely to endow it with greater autonomous facility for lignocellulose digestion than animals such as termites."