Hoover and her colleagues speculated that the beetle could be harboring a community of microbes in the gut, which helps in breaking down lignin.
The researchers compared the chemical structure of non-degraded wood before and after it had passed through the gut of two wood-eating insects. To measure the degree of change in the lignin, they first fed pin oak wood to Asian longhorned beetles. Next they fed ponderosa pine wood to the Pacific dampwood termite, an insect that typically eats only dead wood.
Chemical analyses of feces from the two bugs indicated that they are able to alter the chemical structure of lignin by selectively adding or removing certain groups of molecules from the polymer.
Such alterations, said Geib, make it easier for the insect to break down wood.
"This fungus has genes that then make enzymes," explained Hoover, whose team's findings appear today (Aug. 18) in the Proceedings of the National Academy of Sciences. "We have been able to detect messages from the [fungal] DNA, which get translated into enzymes."
While the researchers have identified the fungus residing in the gut of the Asian longhorned beetle, they have yet to find one in the gut of the termite.
"The types of chemical changes we see in the beetle are similar to those seen in the white-rot fungus," said Geib. "Changes that we see in the termite are similar to those in the brown-rot fungus. The chemical changes to the lignin are similar."
However, Geib cautions that while the gut-borne fungus is certainly a key player in degrading wood, it may just be part of a bigger picture.
"It is likely that there is an interaction among enzymes produced by the fungus, hundreds of bacteria within the insect gut, and the insect itself," explained Geib. "It is a consortium that is doing the job."
If researchers manage to identify some of these key microbes, he says it might be possi
|Contact: Amitabh Avasthi|