If any of you are fans of David Attenborough’s wildlife programmes on the BBC then you might have seen his visit to a termite mound in Africa.
A highlight of that probe was the discovery that termites build air-conditioning systems. Clever little beasts.
They are also smart at digesting plants and are a major pest in hot countries as they can literally devour your house.
It turns out that these colonial insects possess enzymes in their digestive tracts that might be ideal for manufacturing ethanol for use as a biofuel.
Michael Scharf, an assistant professor of entomology at the University of Florida, Gainesville, has been working with termites in a bid to learn more about they way they digest their foods, especially their gut enzymes known as symbionts.
These are produced by both termites and the micro-organisms that inhabit their gut. The reckoning is that these could be utilised to produce ethanol from non-edible plant material such as straw and wood.
“Through millions and millions of years of evolution, termites and their symbionts have acquired highly specialised enzymes that work together to efficiently convert wood and other plant materials into simple sugars,” says Scharf.
“These enzymes are of the most value to bioethanol production.”
Current bioethanol production processes tend to use edible plant materials such as starch from corn (maize) and sugar from sugar cane and, in Europe, sugar beet. These contain easily accessible sugar molecules that can be fermented to produce ethanol.
However, using food crops to produce ethanol has proved increasingly controversial, with bioethanol being blamed for much of the recent steep rise in food prices.
The non-edible parts of many plants also contain a large number of sugar molecules which could, potentially, be used to produce ethanol. But such molecules are far less accessible as they are locked up within a substance known as lignocellulose, which provides structural support for plant-cell walls.
Breaking lignocellulose into its component sugar molecules is far from easy. One approach involves heating it in combination with acids or bases and then exposing the pretreated material to various enzymes. Another approach is very fine grinding followed by enzymatic treatment. Termites, on the other hand, routinely digest wood and other lignocellulosic materials into their component sugars. They appear to prefer the fine grinding approach in combination with their particular set of enzymes.
Through research, it has been possible to identify a number of the main enzymes, many of which could prove useful for producing ethanol. According to Scharf, this work has already provided strong preliminary evidence that the enzymes produced by the termites and their symbionts tend to work collaboratively, with the lignocellulosic material having to be partially digested by termite enzymes before it can be further digested by symbiont enzymes.
It’s early days, but Scharf says: “Once we identify major players (from termites and symbionts), we can test combinations that may have applications in making bioethanol production more feasible.”
Belief is that this kind of digestome analysis could also be applied to other insects that feed on woody material, such as wood-boring beetles and certain wasps and flies.