Mushrooms help beetles digest wood

According to a group of entomologists and biochemists, a small, little-known fungus in the gut of Asian long-horned beetles has helped them chew the hardest wood. As scientists, this discovery could lead to methods to improve pest control, and find more effective ways to break down biomass of plants to produce biofuels. learn.

Microorganisms in insect gut have long been known for their ability to break down the cellulose structure, but people still do not know much about whether or not insects disintegrate lignin. This is a natural pilyme that helps plants stay upright while protecting them from most forms of microbial attack.

Ming Tien, co-author and professor of biochemistry and molecular biology in Pennsylvania state, said: 'Linhin is natural plastic, any creature that wants to take sugar from plants must be able to pass. This protection barrier. We suspect that the fungus in the beetle gut has produced enzymes that help the bug break down Linhin's structure. '

Before the study, it was thought that insects could not break down the structure of the lignin, so we still thought that they ate the decayed wood or they lived near fungi capable of decomposing wood.

But the hypothesis cannot explain the possibility of insects eating wood and growing on healthy living trees.

Tien was supported by Kelli Hoover - co-author and associate professor of entomology in Pennsylvania state - and lead author Scott Geib - student and postdoctoral student in Pennsylvania state - to find an explanation. . Tien said: 'How insects can break the linhin protection wall to reach the vegetation path is still a mystery'.

The Asian longhorned beetle attacks healthy plants, they drill through hardwoods to the inside to reach the fat-rich energy-rich part. At that time the pest of insects originating from China increased its size by 300 times, from the size of a grain of rice to a length of several inches.

Hoover and his colleagues suggest that beetles may have brought the entire microbial community in their gut to help them break down the lignin structure.

Asian long horned beetle larvae live inside the woody stems of early deciduous trees.In the gut it has a modified lignin mushroom that makes it easier to break wood structure.(Photo: Joshua Peter Kaffer)

The researchers compared the chemical structure of un-degraded wood before and after passing through the intestines of two wood-eating insects. To determine the degree of transformation of the lignin, they first fed oak wood to the long-horned beetle. Then fed the Pacific wood-eating termites, this is an insect that only eats wood of dead trees.

Chemists analyzed the droppings of two beetles that showed that they could alter the chemical structure of the lignin by adding or removing certain molecular groups in the polymer.

According to Geib, the transformation helped insects digest wood more easily.

Hoover explains: 'The fungus in the intestine of insects has genes that make necessary enzymes. We were able to find the piece of information on the fungal DNA responsible for enzyme production. ' The team's findings were published on August 18 in the Proceedings of the National Academy of Sciences.

While the researchers were able to identify the fungus that resides in the intestines of Asian long-horned beetles, they have yet to be able to find the fungus in the gut of the termite.

Geib said: 'The kind of chemical change we observed in beetles is similar to that of the white-rot fungus. The transformation that we observed in termites resembled brown rot fungi. The chemical transformation for linhin is similar. '

However, Geib emphasized that although intestinal fungi are undoubtedly a key factor in digesting wood, this is only part of a larger factor.

'There seems to be an interaction between the enzyme produced by the fungus, with hundreds of bacteria in the insect gut and the insect itself. They formed a consortium to do the work. '

If researchers can find some important microorganisms, they can target these microorganisms to prevent the development of Asian longhorned beetles. They are causing serious danger to the wood industry and the plastic-based freshwater industry.

Both Geib and Hoover studied Asian long horned beetles that believed they had found a strange evolutionary adaptation of the insect world.

Hoover said: 'The fungus in the Asian long-horned beetle gut causes diseases in plants. But this bug is very special. Somehow they get the fungus that lives in the gut to help them digest wood. ' The study was funded by the Alphawood Foundation and the Pennsylvania School of Agricultural Sciences.

She also pointed out that the fungus that lives in the beetle gut has a higher yield than their free-living counterparts. While the fungus is free to take months or even years to decompose the wood, the fungus in the beetle gut performs much faster.

Scientists believe that this rapid process could be exploited to produce biofuels.

Geib said: 'Breaking the lignin barrier makes it easier to access cellulose than the most environmentally and costly work to produce ethanol from biomass.' He added that the team's findings could lead to the development of the potential of more economical enzymes that are more efficient to convert wood into ethanol.