Plenty of readily available woody biomass could soon be converted into low-carbon biofuel.
Converting wood into biofuel on a large scale could be a neat development as it would help us wean ourselves off fossil fuels. And the way of doing so, scientists say, is leading through the guts of small marine isopods that bore into decaying wood underwater.
In aquatic environments gribble perform an important ecological role by chewing down pieces of dead wood that have been washed into the sea from river estuaries. Less helpfully, they are also in the habit of consuming wood used in boats and piers, which has not endeared them to fishermen.
How the tiny crustaceans bore through lignin, the sturdy coating around the sugar polymers that compose wood, has been little understood. An international team of scientists say they finally have the answer. By studying gribble’s gut, which is the only known sterile digestive system in any animal, they found that hemocyanin proteins, which transport oxygen through their bodies, enable the tiny organisms to extract sugars from wood.
This discovery, the researchers say, can help us copy the chemical mechanisms involved so that plenty of readily available woody biomass can be converted into low-carbon biofuel. The scientists decided to test their theory by treating wood with hemocyanin proteins.
The result: more than double the usual amount of sugars was released. In fact, it was the same amount that has so far been released only by help of costly thermochemical pre-treatments used in industry.
“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,” explains Prof. Simon McQueen-Mason, a biologist at the University of York who led the research team.
“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,” McQueen-Mason adds.
Woody plant biomass is the most abundant renewable carbon resource on the planet, the researchers point out, so turning some of that readily available biomass into biofuel would come at a lot lower environmental costs than growing crops to do the same. “In the long term this discovery may be useful in reducing the amount of energy required for pre-treating wood to convert it to biofuel,” stresses Prof. Neil Bruce, a biologist at the same British university who was a part of the research team.