Scientists have discovered how shipworms digest wood – and it could have implications for biotech companies and the development of new antibiotics.
First, some basics. Shipworms aren’t worms – they are a group of bivalve molluscs related to clams and oysters, but they have an unusual lifestyle for marine invertebrates. They mostly eat wood and they don’t live in a shell. They have actually modified their shell into a structure that rasps wood into small fragments they can then consume.
They also have an historical claim to fame – shipworms played an important role in the huge losses suffered by the Spanish Armada in 1588. Historians agree that one of the reasons so many ships were wrecked off the coasts of Scotland and Ireland after they were defeated by the British was because they were in poor condition as a result of all the holes inflicted upon them by burrowing worms.
Very few animals can eat trees – termites are another – and those that do usually have specialist microbes in their guts that do the essential job of breaking down the lignin, which is the really tough component of wood.
But there was no evidence of specialist bacteria in a shipworm’s gut. “The shipworm’s digestive tract has long thought to be virtually sterile,” says Barry Goodell, a recently retired professor at the University of Massachusetts Amherst and a co-author on a new paper that has revealed the secret of its success.
After many years of fruitless investigation, a team from UMass and colleagues from other universities took a look at tiny sub-organ of the gut called the typhlosole, and there they found bacteria that can produce enzymes with the ability to break down wood.
Apart from the benefit of solving a salty puzzle, the discovery could be of interest to biotech companies looking for new ways to digest materials that are difficult to break down. Previous symbiotic organisms found within shipworms have had anti-parasitic antibodies, so could the same be true of these newly discovered ones?
A huge quantity of wood ends up in the world’s oceans every year – mangroves alone are estimated to account of nine gigatons of plant biomass, and 70 per cent of mangroves are digested by shipworms. Understanding how this happens will enable climate scientists to refine their models on how carbon dioxide from the breaking down of wood is released into the atmosphere.
More on molluscs and worms:
