Termites studied in quest for green fuels

[Martin Coleman]

California, USA

Researchers have scooped soil near a reservoir in Massachusetts, visited a Russian volcano, and scoured the bottom of the sea looking for microbes that hold the key to new biofuels. Now, they are investigating termites more deeply.

The otherwise dreaded insect is a model bug bioreactor, adept at the difficult task of breaking down wood and turning it into fuel.

Learning the secret of that skill could open the door to creating a new class of plant-based fuels to offset a reliance on petroleum products.

What scientists have learned so far, however, suggests that it will not be easy to duplicate nature.

Over the past year, several studies elucidating termite innards have appeared in mainstream science journals. Last month, Japanese researchers added their own report on just how termites digest wood. A key, they said, can be found within termites' bodies like nested Russian dolls - a bacteria that lives within a microorganism that lives within the termite gut.

It is an intriguing, and complicated, symbiosis.

"We only need to look to nature to get a clear sign this is not going to have a simple solution," said Jared Leadbetter, associate professor of environmental microbiology at the California Institute of Technology, who was not involved in the study. "With 100 million years-plus to streamline this process, you have species living within species, living within species. So we better embrace the fact this is going to have a complex answer."

In a study published last year, Leadbetter and others explored a small sample of termite gut bacteria genes, and found 1,000 involved in breaking down wood.

The new study, which focuses on one of the most voracious of the 2,600 termite species, illustrates yet more complexity. The work, published in the journal Science, shows how a partnership within termite guts helps explain wood digestion.

The microorganism, called P. grassi, breaks down cellulose, a component of wood. A bacteria that lives inside that microorganism provides nitrogen, which is necessary for life, but scarce in wood. Researchers have sequenced the genes of the bacteria and some of the protozoa and are now analyzing the ones involved in digesting cellulose in hopes of better understanding the secrets of the digestion process.

"As a team, we are aiming to find out factors useful for making a novel biofuel," one of the authors, Yuichi Hongoh, of the Ecomolecular Biorecycling Science Research Team at Riken, a research institute in Wako, Japan, wrote in an e-mail.

The challenge of making fuel from rigid plants, like trees, is that they lock away energy in complex molecules.

"Cellulose is a very, very tough molecule. You can hit it with acid - fairly concentrated acid - and it will just sit there," said Alexander DiIorio, director of the bioprocess center at Worcester Polytechnic Institute in Massachusetts. He is looking at everything from termites to rotting wood foraged from local forests in the search for ways to make cellulosic ethanol. His work is funded by the California biofuels company EdenIQ.

Adding to the difficulty is that a rigid material called lignin is woven in with the cellulose. Researchers are looking for a variety of solutions to these problems. In another scourge-turned-science moment, Pennsylvania State University researchers reported this summer that a fungus harbored in the gut of the Asian longhorned beetle that is ravaging maples in the United States could help degrade lignin.

But even when promising enzymes and microbes have been identified, the work is not straightforward.

For example, a microbe discovered in a soil sample from the Quabbin Reservoir in Massachusetts can convert woody plant matter directly into ethanol, according to Sue Leschine, a professor of microbiology at the University of Massachusetts, Amherst. But Qteros, the company she co-founded to work on the microbe, is untangling problems, like how to prepare the raw materials for microbe digestion more cheaply and speed up the process.

Entrepreneurs are moving forward. Mascoma, a cellulosic ethanol company based in Boston, announced in October that it had raised $49.5 million toward building a plant in Michigan.

Verenium, in Cambridge, Massachusetts, built a demonstration plant in Louisiana and is working to extract fuel from materials like bagasse, the remnants of sugar cane.

Verenium, like other companies, is interested in termite innards, but ultimately is taking a much broader approach. It is scanning the great microbiological diversity of the world, agnostic to whether it is from a termite or the rainforest floor.

To see the biofuel problem as a matter of scientific breakthroughs is itself misleading, Leadbetter said, considering the challenges posed by logistical issues like building plants, distribution networks and a supply chain of biomass.

http://www.nytimes.com/2008/12/09/health/09iht-termite.1.18516781.h...