Gut Reactions /3

http://www.theatlantic.com/doc/200809/termites

And it’s too early to tell whether the termite will ever provide genes or information that will enable biofuel production. Termite research could instead provide a cautionary tale about the difficulties of replicating nature on a political schedule. It may be faster and easier to come up with a comprehensive energy policy—investing in energy efficiency, changing personal behavior, and working with other large oil consumers to control prices—than to create a cellulose economy out of the termite gut. Termites certainly have their critics. One is Harvey Blanch, a professor of chemical engineering at UC Berkeley and the chief science and technology officer at the Department of Energy’s Joint Bio-Energy Institute, in Emeryville, California (where Hugenholtz also conducts research). “Those microbes eat pâté!” Blanch said. By the time wood reaches the termite’s third gut, he explained, it has been chewed to a fine consistency and soaked in the highly alkaline second stomach; the gut microbes don’t have to work very hard to break it down. Pretreating wood in similar ways on an industrial scale would be ridiculously expensive, he believes. He thinks the termite has been overhyped, and sees this as a reflection of unrealistically high hopes for quick, painless replacements for gasoline. Blanch has experienced the pitfalls of research driven by political goals. In the early 1970s, he worked on creating faux meat products from petroleum, which was then thought to be a cheap way to feed the world. For example, single-celled “chicken” proteins were produced by yeasts that fed on oil by-products, and then draped around plastic bones. But when the 1973 oil crisis hit, the cost of the raw material soared, effectively ending the petroprotein business. Blanch then shifted to cellulosic ethanol; the project was progressing until President Reagan killed it, in the mid-1980s. Now, he’s at once hopeful that we will one day be able to engineer novel organisms and make better fuels, and wary of putting too much faith in quick technological solutions. “Given the scale at which we need to operate, it’s hard to imagine any magic organism that will do the trick,” he told me. Several years ago, government labs set a goal of producing cellulosic ethanol for $1.33 a gallon by 2012, but Blanch cautions that the retail price could be $6 or $8 a gallon if the cost of the raw materials rises, and he thinks a realistic deadline is at least 10 years away. Perhaps because of his earlier experiences, he fears that projects that fail to deliver quickly are at risk, which puts a lot of pressure on both the Bioenergy Research Centers and individual researchers.
These concerns speak to an important tension underlying the termite research: the often competing agendas of work aimed at producing quick results, and of the slower, more methodical approach known as basic science, which tries to discover the fundamental logic of natural processes. Again, Julia Child (or maybe the more commercial Wolfgang Puck) versus the librarians. Some of the scientists—and even venture capitalists—I spoke with voiced fears that the race to harness nature for fuel production may cause us to neglect basic science and thus jeopardize potential long-term gains. Consider this: half of the 80,000 genes inventoried from the Costa Rican termites remain unidentified, and each of those 40,000, Warnecke imagines, could require a Ph.D. thesis to figure out. Hugenholtz says that metagenomics is grappling with the problem of having too much information and too few references. “Sequencing is far outstripping our ability to characterize the genes,” he explains, adding that this can lead to “genome rot”—a chain of errors created when one scientist gets a gene wrong, and then the mistake is multiplied across other genomes. The popular model of science is based on “eureka” moments, but right now, metagenomics is more like a big 3-D puzzle, where every new piece of knowledge—and every mistake—affects the whole. Trying to solve just one part of the puzzle for a quick commercial breakthrough may be as tricky as solving the entire thing. It could also cause us to give short shrift to alternative solutions. Eric Mathur was one of the Diversa executives who helped set up the Costa Rican expedition; he now works for Synthetic Genomics, a company founded by the scientific impresario Craig Venter to search for biology-based fuels and methods to cut greenhouse-gas emissions. Mathur says the Nature paper is just the beginning of a long process of understanding how symbiotic creatures deal with wood and carbon. He thinks that searching for individual enzymes in the termite will be a dead end, but that harnessing the power of whole environments might yield results. The challenge, he says, is to learn how these environments’ overall metabolisms work, and then use the tools of synthetic biology to engineer the organisms in them to evolve—creating a “slave organism” that focuses all of its resources, down to its last electron, on processing carbon. “Metabolic engineering is a very powerful method for productivity,” he told me. But the strongest argument for more basic research may be the termite itself. Jared Leadbetter, an associate professor of environmental microbiology at Caltech, remembers feeling “like an ecotourist in Alice in Wonderland” the first time he looked at a magnified termite gut, 18 years ago. Leadbetter has pioneered the study of the metabolism of a few of the spiro­chetes in the gut. Like Mathur, he believes scientists might put the termite’s gut to work against global warming by using it to understand and possibly alter the carbon cycle—the biogeochemical give-and-take of greenhouse gases between the Earth and its atmosphere. Leadbetter says one of the extraordinary things about termites is not how much ethanol they might make, but how little methane they produce. Cows lose 20 percent of the energy in the grass they eat, because the microbes in their stomachs combine hydrogen and carbon dioxide from the grass to make methane, a greenhouse gas that traps 20 times as much heat in the atmosphere as CO2. In 2006, the greenhouse gases produced by U.S. farm animals exceeded the emissions of the iron, steel, and cement industries combined. Termites lose less than 2 percent of their nutrients to methane production, because the spirochetes in their guts transform hydrogen and carbon dioxide into acetate, which the termites use as fuel. If we understood this process, perhaps we could put new microorganisms into the stomachs of cows and reduce their production of methane. We’re a long way from changing the chemistry of cows’ stomachs, but the process of adapting and commercializing the termite’s role in the carbon cycle has already yielded success on a small scale. The Virginia-based company ArcTech trained termites to eat coal, and then rummaged through their guts to find the microorganisms best at turning coal into methane. It cultured those microorganisms and now feeds them coal; the company plans to use the methane they produce to make electricity, and is already selling the by-products, including one used by farmers as a soil additive. ArcTech says this method eliminates virtually all greenhouse-gas emissions from coal-based electricity production. Other companies are trying to engineer similar organisms that could be sent into abandoned mines and oil wells to scavenge fuel that goes unused because it is so hard to get at. Such efforts could have a dramatic effect on both the environment and geopolitics: experts estimate that increasing the yield of oil wells from the current average of 35 percent of the oil in a reservoir to 40 percent would be the equivalent of discovering a new Saudi Arabia. Who knows what other answers may lurk in the termite? Elizabeth Ottesen, a graduate student doing research in Leadbetter’s lab, dissected a termite and put it under a microscope to give me a tour of its gut. At first glance, the dark mass of the gut was immobile, the organisms apparently packed too tightly to move, but as Ottesen added water, a menagerie of blobby Trichonympha, whizzing spirochetes, and other creatures materialized, all supported by gangs of bacteria too small to see. The inhabitants here are arranged in hierarchies more elaborate than Manhattan real estate, she said: Those at the edges use oxygen, while those in the middle are anaerobes. Many are high-speed commuters, outfitted with complicated sensing and swimming apparatus that helps them find hydrogen and other gases. Among the creatures in the termite’s gut, and especially among those creatures’ genes, exist redundancies that suggest the system has been over­engineered to survive the worst (including being force-fed coal). A spirochete’s flagella, for example, are between the layers of a double skin, enabling the organism to drill through the most viscous environments. Leadbetter expects it will take at least 25 years to unravel what he calls the “teleological questions” about the termite’s complexity. Along the way, the termite will likely provide clues to solving climate change, but Leadbetter thinks its greatest value may be as a repository of biological wisdom gathered over the course of more than 100 million years of survival on Earth. “When you look at a termite and its gut,” he says, “you’re looking at a long line of winners.”