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A SMALL marine creature which lives solely on wood could hold the key to commercial cellulosic biofuel, according to UK researchers.

The gribble (pictured) is a marine crustacean usually less than 0.5 cm in length which bores into wood for food. Bored wood becomes brittle, and gribbles have long plagued owners of wooden boats and structures such as wooden jetties. Researchers at the BBSRC (Biotechnology and Biological Sciences Research Council) Sustainable Bioenergy Centre at the Universities of York and Portsmouth looked at one particular species of gribble – Limnoria quadripunctata to try to determine how it breaks down the wood. The gribble is apparently unique amongst wood-eating creatures in that it does not contain symbiotic enzyme-producing microorganisms and must therefore produce all its own enzymes.

A team headed by biologists Simon McQueen-Mason and Neil Bruce at York’s Centre for Novel Agricultural Products (CNAP), and Simon Cragg at Portsmouth’s Institute of Marine Sciences looked at genes expressed in the guts of the gribble to find which enzymes are produced. They discovered the gribble’s gut enzymes are dominated by glycosyl hydrolase, a cellulose enzyme previously only found in wood-degrading fungi and the microorganisms in the digestive systems of termites. 

The team also discovered that the gribble also likely produces larger than usual quantities of haemocyanin, a copper-containing respiratory protein. Recent studies on haemocyanin have suggested that it functions as a phenoloxidase, which breaks down lignin.

The next step in the research will be to study how the enzymes work and how to adapt them to industrial applications.

The research was published in Proceedings of the National Academy of Sciences (doi: 10.1073/pnas.0914228107).