Genetic Underpinnings of Wood Digestion by Termite Gut Microbes Revealed

PASADENA, Calif.--When termites are chewing on your home, your immediate thought probably isn't "I wonder how they digest that stuff?" But biologists have been gnawing on the question for more than a century. The key is not just the termite, but what lives in its gut. A multitude of genes from the microbes populating the hindgut of a termite have been sequenced and analyzed, and the findings reported today in the journal Nature.

California Institute of Technology associate professor of environmental microbiology Jared Leadbetter led a team of researchers from other universities, private industry, and the Department of Energy (DOE) in uncovering the genetic underpinnings and the roles of bacteria in wood digestion by "higher termites." These insects abound in tropical and subtropical ecosystems. What the team found, says Leadbetter, is "a comprehensive set of blueprints for the bacteria that help dismantle wood."

Prior to this study, only one gene--in the insect itself--had been connected to the termite's rare ability to digest and nourish itself with wood, a substance that is energy-rich but hard to break down. It had also long been suspected that the 250 bacterial species that crowd the pinhead volume of a higher termite's hindgut might be directly involved in the process. But there was no way of knowing their roles for sure, because most of the organisms die quickly when removed from their host. Although the first bacterium genome was sequenced in 1994, it was a few years before scientists even considered sequencing entire communities of multiple species of organisms.

Leadbetter and his colleagues proposed to the DOE Joint Genome Institute (JGI) that the gut community of the Costa Rican termite Nasutitermes be examined because it is abundant and it plays significant roles in the wood degradation that helps to renew ecosystems. Leadbetter joined forces with collaborators at JGI, Verenium Corporation's San Diego facilities, and INBio, the National Biodiversity Institute of Costa Rica. They sequenced and analyzed more than 80,000 genes encoded by many of the hindgut bacteria species. "This was a fairly risky project when we proposed it," says Leadbetter, because "in these abundant tropical termites, there was no compelling evidence that these microbes play direct roles in cellulose degradation."

When the results started coming in, "we all breathed a big sigh of relief, because it turned out to be a gold mine in there," Leadbetter says. They found nearly 1,000 genes that underlie roles in breaking down two of wood's main components, cellulose and xylan, into their component sugars. The degradation of cellulose and xylan requires an arsenal of enzymes because of the huge diversity of biochemical bonds in wood. "This isn't some soft paper or grass we're talking about," says Leadbetter. "It's a hard substrate." Wood is made of three tightly intertwined compounds; taking it apart is a challenge, and termites are among the few known animals that can do it.

Leadbetter and his colleagues hope to eventually uncover exactly how each gene is involved in degrading wood, and where the energy the termite derives from the wood goes. This has recently become a focus of interest for those interested in developing an effective, industrial method to convert wood into ethanol. The challenge lies in events at the start of the process, like those involved in breaking down cellulose and xylan. Leadbetter and his colleagues believe that by investigating the genes that underlie these primary reactions, better ways of manufacturing biofuel can eventually be developed.

The study also identified nearly 100 different species of bacteria called spirochetes that belong to the genus Treponema. This membership makes them closely related to the bacterium that causes syphilis and to other spirochetes implicated in Lyme disease and gum disease. In termites, though, the findings show that these spirochetes actually benefit the health of their hosts. The genome sequencing also showed that the spirochetes are active in processes that generate hydrogen, an energy-rich gas, from wood. Certain genes also indicate that gut spirochetes can essentially taste or smell hydrogen and will swim either to or from its sources in the gut. In general, Leadbetter says, it looks like "these bacteria differ from those that dominate the gut tracts of humans and other mammals in their broad capacity to swim in response to diverse chemical stimuli. This behavior may be relevant to effective wood degradation."

Other Caltech authors of the paper are Eric Matson, a postdoctoral scholar in environmental science and engineering; Xinning Zhang, a graduate student in environmental science and engineering; and Elizabeth Ottesen, a graduate student in biology. Group leaders are Dan Robertson of Verenium Corporation, Phil Hugenholtz of the JGI, Giselle Tamayo of INBio, and Eric Mathur, formerly of Diversa (now at Synthetic Genomics).

Elisabeth Nadin

New Method of Studying Ancient Fossils Points to Carbon Dioxide As a Driver of Global Warming

PASADENA, Calif.—A team of American and Canadian scientists has devised a new way to study Earth's past climate by analyzing the chemical composition of ancient marine fossils. The first published tests with the method further support the view that atmospheric CO2 has contributed to dramatic climate variations in the past, and strengthen projections that human CO2 emissions could cause global warming.

In the current issue of the journal Nature, geologists and environmental scientists from the California Institute of Technology, the University of Ottawa, the Memorial University of Newfoundland, Brock University, and the Waquoit Bay National Estuarine Research Reserve report the results of a new method for determining the growth temperatures of carbonate fossils such as shells and corals. This method looks at the percentage of rare isotopes of oxygen and carbon that bond with each other rather than being randomly distributed through their mineral lattices.

Because these bonds between oxygen-18 and carbon-13 form in greater abundance at low temperatures and lesser abundance at higher temperatures, a precise measurement of their concentration in a carbonate fossil can quantify the temperature of seawater in which the organisms lived. By comparing this record of temperature change with previous estimates of past atmospheric CO2 concentrations, the study demonstrates a strong coupling of atmospheric temperatures and carbon dioxide concentrations across one of Earth's major environmental shifts.

According to Rosemarie Came, a postdoctoral scholar in geochemistry at Caltech and lead author of the article, only about 60 parts per million of the carbonate molecular groups that make up the mineral structures of carbonate fossils are a combination of both oxygen-18 and carbon-13, but the amount varies predictably with temperature. Therefore, knowing the age of the sample and how much of these exotic carbonate groups are present allows one to create a record of the planet's temperature through time.

"This clumped-isotope method has an advantage over previous approaches because we're looking at the distribution of rare isotopes inside a single shell or coral," Came says. "All the information needed to study the surface temperature at the time the animal lived is stored in the fossil itself."

In this way, the method contrasts with previous approaches that require knowledge of the chemistry of seawater in the distant past--something that is poorly known.

The study contrasts the growth temperatures of fossils from two times in the distant geological past. The Silurian period, approximately 400 million years ago, is thought to have been a time of highly elevated atmospheric CO2 (more than 10 times the modern concentration), and was found by the researchers to be a time of exceptionally warm shallow-ocean temperatures—nearly 35 degrees C. In contrast, the Carboniferous period, roughly 300 million years ago, appears to have been characterized by far lower levels of atmospheric carbon dioxide (similar to modern values) and had shallow marine temperatures similar to or slightly cooler than today-about 25 degrees C. Thus, the draw-down of atmospheric CO2 coincided with strong global cooling.

"This is a huge change in temperature," says John Eiler, a professor of geochemistry at Caltech and a coauthor of the study. "It shows that carbon dioxide really has been a powerful driver of climate change in Earth's past."

The title of the Nature paper is "Coupling of surface temperatures and atmospheric CO2 concentrations during the Paleozoic era." The other authors are Jan Veizer of the University of Ottawa, Karem Azmy of Memorial University of Newfoundland, Uwe Brand of Brock University, and Christopher R. Weidman of the Waquoit National Estuarine Research Reserve, Massachusetts.

Robert Tindol

Some Earth-like Worlds May Have Foliage of Colors Other Than Green, Researchers Say

PASADENA, Calif.—In the next decade, when scientists are able to study Earth-sized worlds around other stars, they may find that foliage on some of the planets is predominantly yellow—or orange, or red. It all depends on the color of the star the planet orbits and the stuff that makes up the planet's atmosphere.

That's the conclusion of researchers from the Virtual Planetary Laboratory, a NASA-funded initiative at the California Institute of Technology, who are announcing today results from a series of comprehensive computer models for guiding the future search for plant life on other worlds. Two related papers on what to expect out of photosynthesis are being issued in the journal Astrobiology.

Determining the range of possible colors is important because scientists need to know what to look for when they begin getting spectra of light from faraway Earth-sized planets, says lead author Nancy Kiang, a biometeorologist at NASA's Goddard Institute for Space Studies, and currently a visitor at Caltech's Spitzer Science Center.

"The dominant color of photosynthesis could be yellow, or orange, or maybe red," Kiang explains. "I think it is unlikely that anything will be blue—and, of course, green plants are also a possibility, since that's what we have here."

"What makes this study unusual is the highly interdisciplinary method by which planetary scientists, atmospheric scientists, biologists, and others have pooled their efforts in modeling the possible spectra of light available to plants on Earth-like planets orbiting around other stars," says Vikki Meadows, an astrobiologist at Caltech and lead scientist of the Virtual Planetary Laboratory. Because the study requires data about everything from the type of photons given off by a main-sequence star in a particular stage of its life, to the depth of water that an aqueous plant might prefer, a huge variety of information is required.

"No single astronomer or biologist or atmospheric scientist could have attacked this problem individually to get the simulation," says Meadows, who is herself an astrobiologist whose original academic training was in astronomy. "So these papers are truly interdisciplinary pieces of work."

The researchers focused on the way plants use light for energy to produce sugar—which is pretty much the definition of photosynthesis—because photosynthetic pigments must be adapted to the available light spectrum. The available light spectrum at a planet's surface is a result of both the light from the parent star and filtering effects of gases in the atmosphere. For example, ozone absorbs ultraviolet light, so that not much reaches Earth's surface.

"It turns out that the spectrum of the number of particles of light is what is important, and on Earth there are more particles in the red," Kiang explains. "This could explain why plants here on Earth are mainly green."

On Earth, plants absorb blue light because it is energetic, and red light because the photons are plentiful. There is more than enough energy from the blue and red in sunlight, so plants do not really need more. Therefore, they reflect away relatively more green light, which is why plants appear green to us.

A planet orbiting a star with the size and temperature roughly like our sun, and with Earth's particular mix of oxygen and what-have-you, would tend to have plants that like to soak up light in blue and red and less in green. But the situation could be different on other planets, where other colors of the spectrum might predominate. In those cases, another color like red might not be so useful, and the plants would mostly appear red.

There are many other factors, such as the role not only ozone plays but also carbon dioxide and water vapor, how the stellar radiation creates chemical reactions in the atmosphere, whether the star is prone to solar flares, how much water is on the planet, how much light gets to the surface, what gases are produced by the plants themselves, and so on. This is why a complex computer model was necessary.

Also, one might wonder what things could live on a planet with very little ozone, for example, where radiation would be a daily assault on living organisms, and energetic particles from solar winds would be like deadly microscopic bullets. Meadows says the modelers have taken such scenarios into consideration, and they think that there might be a "sweet spot" a few to tens of feet below the surface of the water where life is protected from UV radiation.

"We found that the sweet spot could be up to nine meters underwater for a planet orbiting a star significantly cooler than our sun, and photosynthesis could still take place," she says. "Something with a floatation capability could be protected from solar flares and still get enough photons to carry on."

In short, the new model provides a powerful tool for looking for life on other worlds, Meadows says.

"We once thought that planets around other stars were exceedingly rare," she explains. "But every time telescopes have gotten better, we've been able to find more and more Jupiter-sized planets. So there's no reason to think that there aren't a huge number of Earth- sized planets out there as well.

"We may not find anything like ourselves, but it's possible that bacterial life is prevalent on these Earth-like planets," Meadows adds. "If we have the environment for life to exist, then we think that it's likely that life will emerge in these conditions."

The other authors of the two papers are Antigona Segura-Peralta, Giovanna Tinetti, Martin Cohen, Janet Siefert, and David Crisp, all of the Virtual Planetary Laboratory, Govindjee, of the University of Illinois, and Robert Blankenship, of Washington University.

The Virtual Planetary Laboratory was formed as part of the NASA Astrobiology Institute, which was founded in 1997 as a partnership between NASA, 12 major U.S. teams, and six international consortia. NAI's goal is to promote, conduct, and lead integrated multidisciplinary astrobiology research and to train a new generation of astrobiology researchers.

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Robert Tindol

Caltech, UCLA, and UCSD Host ConferenceTo Address Clean Alternative Energy

PASADENA, Calif.—The latest in clean alternative-energy resources and the promise for transportation will be the focus of the California Clean Innovation 2007 (CACI) conference to be held Friday, May 11, on the campus of the California Institute of Technology. The conference is open to the public by registration.

According to one of the conference's main organizers, Siddharth Dasgupta, who is associate director of Caltech's NSF Center for Science & Engineering of Materials (CSEM), the all-day event has been designed to provide an inside look at the latest research, to address the challenges ahead, to provide information for entrepreneurs searching for new opportunities in alternative clean energy, and to provide networking opportunities for private- and public-sector professionals.

Conference session topics will include "Clean Power: Solar and Wind," "Clean Transportation: Fuels, Engine, and Storage," "Global Clean Tech Perspectives," and "Private and Public Market Finance." A fast-pitch business-case competition will also be held for student-friendly companies.

Keynote speakers will be Vinod Khosla, founder of Khosla Ventures, and Nate Lewis, the Argyros Professor and professor of chemistry at Caltech whose research is heavily involved in alternative-energy technologies.

Activities begin at 8:30 a.m. with opening comments from Caltech president Jean-Lou Chameau, whose own research interests have included environmental engineering. Lewis's keynote address, "Our Energy Reality," will follow at 8:40 a.m.

The first session, on "Popular Clean Power" will begin at 9:15 a.m., moderated by Art Ellis, vice chancellor for research at UC San Diego. Presentations will be given on solar photovoltaic cells by Harry Atwater, an applied physicist and director of CSEM at Caltech; thin film solar technologies by Billy Stanbery, CEO of Heliovolt; building integrated wind turbine development by Paul Glenney, director of Energy Initiatives at AeroVironment; and large-scale wind innovation by Leif Anderson of Suzlon Energy.

The second-session panel, on transportation fuels, will be moderated by Jose-Luis Contreras of Navigant Consulting. Panelists will be Kevin Gray, director of Alternative Fuels at Diversa on biofuels, Richard Hamilton, CEO of CERES on biofuels, and Vasilios Manousiouthakis, director of UCLA's Hydroegen Energy Research Consortium.

The third-session panel, on fuel cells and hydrogen, will be moderated by Terry Tamminen, an adviser to Governor Arnold Schwarzenegger. Panelists will include Brent Fultz of Caltech on hydrogen storage, Justin Ward of Toyota Hybrid Vehicle Technologies, Mike Gorman, director of transportation products at United Technologies, and Sossina Haile of Caltech on solid acid fuel cells.

In parallel with this session there will be the first round of fast pitch business case competition. Ten teams will make three-minute fast pitches to a panel, which will select three finalists for the final round later in the afternoon.

The afternoon sessions begin with the fourth panel discussion on private and public investment, and will be moderated by Scott McGaraghan, director of business development at EnerNoc. Panelists will be John Rockwell, managing director of Draper Fisher Jurvetson Element, Jim McDermott, managing director of U.S. Renewables, and Mark Huang, senior vice president at GE Energy Financial Services.

The parallel fifth session is on the Global Clean Energy Landscape, moderated by Jim Davis, president of Chevron Energy Solutions. Woody Clark, senior fellow of the Milken Institute will talk about China, Jeremy Martin, energy director of UCSD's Insitute of Americas will talk about South America, and Suvi Sharma, CEO of Solaria will talk about India.

These will be followed by the fast-pitch competition finals leading to the closing keynote by Vinod Khosla and comments by Dean Judy Olian of UCLA's Anderson School of Management. There will be a social mixer at the end from 5 to 7 p.m. for attendees to network with the panelists, keynotes, and each other.

The fee for registration is $150 for the general public, with an "early-bird" registration of $100 until April 15. The registration for students is $35. Online registration and additional information is available at


Robert Tindol

Geologists Provide New Evidence for Reason Behind Rise of Life in Cambrian Period

PASADENA, Calif.—Geologists have uncovered evidence in the oil fields of Oman that explains how Earth could suddenly have changed 540 million years ago to favor the evolution of the single-celled life forms to the multicellular forms we know today.

Reporting in the December 7 issue of the journal Nature, researchers from MIT, the California Institute of Technology, and Indiana University show that there was a sudden change in the oxygenation of the world's oceans at the time just before the "Cambrian explosion," one of the most significant adaptative radiations in the history of life. With a increased availability of oxygen, the team speculates, single-celled life forms that had dominated the planet for the previous three billion years were able to evolve into the diverse metazoan phyla that still characterize life on Earth.

"The presence of oxygen on Earth is the best indicator of life," says coauthor John Grotzinger, the Fletcher Jones Professor of Geology at Caltech and an authority on sedimentary geology. "But it wasn't always that way. The history of oxygen begins about two and a half billion years ago and occurs in a series of steps. The last step is the subject of this paper."

The key insight was derived when Grotzinger's student Dave Fike, who is lead author of the paper, analyzed core samples and drillings taken at a depth of about three kilometers from oil wells in Oman, which are known to have the oldest commercially viable oil on the planet. The results of carbon and sulfur isotopic analyses from the material led the team to the conclusion that the oceanic conditions that laid down the deposits originally in Oman were quite different from conditions of today.

"You need a very different ocean for these conditions to exist—more like the Black Sea of today, with an upper oxidized layer and lower reduced layer with very little oxygen," says Grotzinger. "The ocean today is pretty well oxidized at all layers, but the ocean before the Cambrian period must have been very different."

When organic matter falls into an ocean that doesn't stir, it becomes deprived of sufficient oxygen and cannot survive as multicellular forms. For this reason, with a limited amount of oxygen, life continued in its single-celled form for the first three billion years.

But about 550 million years ago, according to the team's geologic evidence, the deep ocean began mixing its contents with the shallow ocean, resulting for the first time in a fully oxidized deep ocean.

Characterizing the study as paleoceanography, Grotzinger says the evidence is persuasive because it is so clearly evident in the rock record. Geologists have long believed that the rise of oxygen was a key element involved in the Cambrian radiation, so this discovery really helps solidify that hypothesis.

The oxygen trigger helps account for how life 500 million years ago could have gone from its single-celled existence to the emergence just 10 to 15 million years later of all the metazoan phyla we know today. In short, an abrupt increase in the availability of oxygen may have led to the diversity and complexity of life.

Fike is a graduate student at MIT who is currently in residence at Caltech to work with his professor, Grotzinger, who himself came to Caltech from MIT last year. The other authors of the paper are Lisa Pratt of Indiana University and Roger Summons of MIT.

Robert Tindol

Geobiologists Solve "Catch-22 Problem" Concerning the Rise of Atmospheric Oxygen

PASADENA, Calif.—Two and a half billion years ago, when our evolutionary ancestors were little more than a twinkle in a bacterium's plasma membrane, the process known as photosynthesis suddenly gained the ability to release molecular oxygen into Earth's atmosphere, causing one of the largest environmental changes in the history of our planet. The organisms assumed responsible were the cyanobacteria, which are known to have evolved the ability to turn water, carbon dioxide, and sunlight into oxygen and sugar, and are still around today as the blue-green algae and the chloroplasts in all green plants.

But researchers have long been puzzled as to how the cyanobacteria could make all that oxygen without poisoning themselves. To avoid their DNA getting wrecked by a hydroxyl radical that naturally occurs in the production of oxygen, the cyanobacteria would have had to evolve protective enzymes. But how could natural selection have led the cyanobacteria to evolve these enzymes if the need for them didn't even exist yet?

Now, two groups of researchers at the California Institute of Technology offer an explanation of how cyanobacteria could have avoided this seemingly hopeless contradiction. Reporting in the December 12 Proceedings of the National Academy of Sciences (PNAS) and available online this week, the groups demonstrate that ultraviolet light striking the surface of glacial ice can lead to the accumulation of frozen oxidants and the eventual release of molecular oxygen into the oceans and atmosphere. This trickle of poison could then drive the evolution of oxygen-protecting enzymes in a variety of microbes, including the cyanobacteria. According to Yuk Yung, a professor of planetary science, and Joe Kirschvink, the Van Wingen Professor of Geobiology, the UV-peroxide solution is "rather simple and elegant."

"Before oxygen appeared in the atmosphere, there was no ozone screen to block ultraviolet light from hitting the surface," Kirschvink explains. "When UV light hits water vapor, it converts some of this into hydrogen peroxide, like the stuff you buy at the supermarket for bleaching hair, plus a bit of hydrogen gas.

"Normally this peroxide would not last very long due to back-reactions, but during a glaciation, the hydrogen peroxide freezes out at one degree below the freezing point of water. If UV light were to have penetrated down to the surface of a glacier, small amounts of peroxide would have been trapped in the glacial ice." This process actually happens today in Antarctica when the ozone hole forms, allowing strong UV light to hit the ice.

Before there was any oxygen in Earth's atmosphere or any UV screen, the glacial ice would have flowed downhill to the ocean, melted, and released trace amounts of peroxide directly into the sea water, where another type of chemical reaction converted the peroxide back into water and oxygen. This happened far away from the UV light that would kill organisms, but the oxygen was at such low levels that the cyanobacteria would have avoided oxygen poisoning.

"The ocean was a beautiful place for oxygen-protecting enzymes to evolve," Kirschvink says. "And once those protective enzymes were in place, it paved the way for both oxygenic photosynthesis to evolve, and for aerobic respiration so that cells could actually breathe oxygen like we do."

The evidence for the theory comes from the calculations of lead author Danie Liang, a recent graduate in planetary science at Caltech who is now at the Research Center for Environmental Changes at the Academia Sinica in Taipei, Taiwan.

According to Liang, a serious freeze-over known as the Makganyene Snowball Earth occurred 2.3 billion years ago, at roughly the time cyanobacteria evolved their oxygen-producing capabilities. During the Snowball Earth episode, enough peroxide could have been stored to produce nearly as much oxygen as is in the atmosphere now.

As an additional piece of evidence, this estimated oxygen level is also sufficient to explain the deposition of the Kalahari manganese field in South Africa, which has 80 percent of the economic reserves of manganese in the entire world. This deposit lies immediately on top of the last geological trace of the Makganyene Snowball.

"We used to think it was a cyanobacterial bloom after this glaciation that dumped the manganese out of the seawater," says Liang. "But it may have simply been the oxygen from peroxide decomposition after the Snowball that did it."

In addition to Kirschvink, Yung, and Liang, the other authors are Hyman Hartman of the Center for Biomedical Engineering at MIT, and Robert Kopp, a graduate student in geobiology at Caltech. Hartman, along with Chris McKay of the NASA Ames Research Center, were early advocates for the role that hydrogen peroxide played in the origin and evolution of oxygenic photosynthesis, but they could not identify a good inorganic source for it in Earth's precambrian environment.

The paper is available online at the following Web address:

Robert Tindol

Moore Foundation Gives $6.5 Million to Caltech For Research on Solar-Driven Energy

PASADENA, Calif.—The Gordon and Betty Moore Foundation has awarded $6.5 million to found the Center for Sustainable Energy Research at the California Institute of Technology. The center will conduct research on solar-driven renewable-energy sources. The six-year grant targets various promising technologies that could result in cheap alternatives to fossil fuels.

According to Harry Atwater, the Howard Hughes Professor and professor of applied physics and materials science, the goal of the center is develop the technologies that will transform the industrialized world from one powered by fossil fuels to one that is powered by sunlight. More energy from sunlight strikes the earth in one hour than all of the fossil energy consumed on the planet in a year—so what is missing is not the solar energy, but the science and engineering innovations to use it.

"This new center is the beginning of a major campus effort to address future energy needs," says Atwater, adding that the center will focus on several avenues of research, first taking on technologies pertaining to solar-driven generating methods for fuels such as hydrogen or methanol.

"Splitting water into hydrogen and oxygen using sunlight is a grand challenge because it is the confluence of a number of hard problems," says Atwater. "But success would enable us to either generate and use hydrogen directly as a carbon-free chemical fuel, if society elects to burn the hydrogen by itself, or convert hydrogen to another hydrocarbon fuel like methanol by a carbon-neutral process, if we decide that is the way to go."

Fuel cells using methanol that's made from renewable sources would be carbon-neutral because carbon dioxide would both be consumed and emitted in equal quantities by the reactions for fuel generation and use.

"Which is better? That's the subject of enormous debate," Atwater says. "Currently, we have a liquid-fuel economy, and methanol would have the advantage of being another liquid. However, a hydrogen-as-fuel future would enable us to realize the dream of a fuel that's pollution-free both locally and globally.

"But the biggest challenge is to find a way to split water with sunlight that is robust, efficient, and replaces the platinum catalyst with something that is scalable to terawatts of energy. So platinum is out."

In sum, the Center for Sustainable Energy Research is looking at several technologies to accomplish the goal of providing fossil-fuel alternatives, and several research groups at Caltech are applying their individual expertise to various parts of the problem. Replacing the platinum catalyst, for example, is the goal of Professor of Chemistry Jonas Peters, who has had success with using cobalt as a catalyst. Working on different aspects of solar conversion are Harry Gray, the Arnold O. Beckman Professor of Chemistry, and Nate Lewis, the George L. Argyros Professor and professor of chemistry. Sossina Haile, professor of materials science and chemical engineering, is working on improving fuel cells.

Haile says that society should look toward new possibilities for the future in terms of energy technology rather than scrambling at the last minute when existing options become scarce. "There's an anonymous quote that the Stone Age didn't end because we ran out of stones," she says.

"There is little question that sustainable energy is the grand challenge of our century," Haile adds. "The Moore Foundation has recognized the urgency of the situation. With the foundation's generous support, we will explore radical new ways of addressing all parts of the energy cycle, its generation, its distribution, and its consumption—starting with the basic premise that sunlight provides the planet with more than ample energy to meet our global demands.

"In the fuel-cell portion of the work, we focus on efficient conversion of chemical energy to electricity. And by designing fuel cells that are not restricted to hydrogen as the fuel, we relax the requirement that the world develop a hydrogen storage and delivery infrastructure before the many benefits of fuel cells can be realized."

Atwater says that the Moore Foundation funding is a crucial beginning for the center that could encourage the energy sector to invest more heavily in research and development of alternative sources of energy.

"We hope the center will become a rallying point on campus for work on renewable-energy sources of many kinds," he says. "The solar-driven fuel cycle is our initial effort, but we'll become involved in other promising renewal-energy research opportunities as time goes on."

"I think the story over the next few years will be steady progress on the individual areas of research, guided by the long-term goal of integrating them all together."

The Gordon and Betty Moore Foundation was established in 2000 and seeks to develop outcome-based projects that will improve the quality of life for future generations. It has organized the majority of its grant making around large-scale initiatives and concentrates funding in three program areas: environmental conservation, science, and the San Francisco Bay Area.

Robert Tindol
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Caltech and BP Team Up to Improve Electricity-Producing Solar Cells

PASADENA, Calif.—The California Institute of Technology has teamed up with the energy company BP to look for better and cheaper ways of producing solar cells. The goal of the program is to make the cost of solar electricity more competitive by increasing the current efficiency levels of solar cells.

The program is to be announced June 27 at the Photovoltaics Summit 2006 in San Diego. For an initial five-year period, researchers at Caltech and BP will explore a method of growing silicon by creating arrays of nanorods rather than by casting ingots and cutting wafers, which is the current conventional way of producing silicon for solar cells. Nanorods are small cylinders of silicon that can be 100 times smaller than a human hair and would be tightly packed in an array like bristles in a brush.

A solar cell made up of an array of nanorods will be able to efficiently absorb light along the length of the rods while also collecting the electricity generated by sunlight more efficiently than a conventional solar cell.

The Caltech solar nanorod program will be directed by Nate Lewis, the George L. Argyros Professor and professor of chemistry, and Harry Atwater, the Howard Hughes Professor and professor of applied physics and materials science. In addition, eight postdoctoral researchers and graduate students will work on the project.

"Nanotechnology can offer new and unique ways to make solar-cell materials that are cheaper yet could perform nearly as well as conventional materials," says Lewis, an expert in surface chemistry and photochemistry.

Lewis's group will investigate uses of nanotechnology to create designer solar-cell materials, from nanorods to nanowires, in order to change the conventional paradigm for solar-cell materials.

"Using nanorods as the active elements opens up very new approaches to design and low-cost fabrication of high-performance solar cells," adds Atwater, an expert in electronic and optoelectronic materials and devices.

Atwater's group will investigate ways of creating silicon-based single-junction and compound semiconductor-multijunction nanorod solar cells using vapor-deposition synthesis methods that are scalable to very large areas.

According to BP officials, the research contract is part of the company's long-term technology strategy and is in keeping with its practice of partnering with the world's leading universities on key technology challenges. The program is also aligned with Alternative Energy, a new business launched by BP in November 2005 that is focused on developing low-carbon options for the power industry.

BP Solar's CEO and president, Lee Edwards, said, "This program represents a significant commitment by BP to the long-term potential of solar energy and complements our existing technology programs with the promise for major breakthroughs in solar technology. "Nanorod technology offers enormous promise. However, like any new technology, challenges remain to be solved to make it commercially viable at scale."

Robert Tindol

North Atlantic Corals Could Lead to Better Understanding of the Nature of Climate Change

PASADENA, Calif.—The deep-sea corals of the North Atlantic are now recognized as "archives" of Earth's climatic past. Not only are they sensitive to changes in the mineral content of the water during their 100-year lifetimes, but they can also be dated very accurately.

In a new paper appearing in Science Express, the online publication of the American Association for the Advancement of Science (AAAS), environmental scientists describe their recent advances in "reading" the climatic history of the planet by looking at the radiocarbon of deep-sea corals known as Desmophyllum dianthus.

According to lead author Laura Robinson, a postdoctoral scholar at the California Institute of Technology, the work shows in principle that coral analysis could help solve some outstanding puzzles about the climate. In particular, environmental scientists would like to know why Earth's temperature has been holding so steadily for the last 10,000 years or so, after having previously been so variable.

"These corals are a new archive of climate, just like ice cores and tree rings are archives of climate," says Robinson, who works in the Caltech lab of Jess Adkins, assistant professor of geochemistry and global environmental science, and also an author of the paper.

"One of the significant things about this study is the sheer number of corals we now have to work with," says Adkins, "We've now collected 3,700 corals in the North Atlantic, and have been able to study about 150 so far in detail. Of these, about 25 samples were used in the present study.

"To put this in perspective, I wrote my doctoral dissertation with two dozen corals available," Adkins adds.

The corals that are needed to tell Earth's climatic story are typically found at depths of a few hundred to thousands of meters. Scuba divers, by contrast, can go only about 50 to 75 meters below the surface. Besides, the water is bitter cold and the seas are choppy. And to add an additional complication, the corals can be hard to find.

The solution has been for the researchers to take out a submarine to harvest the coral. The star of the ventures so far has been the deep-submergence vehicle known as Alvin, which is famed for having discovered the Titanic some years back. In a 2003 expedition several hundred miles off the coast of New England, Alvin brought back the aforementioned 3,700 corals from the New England Seamounts.

The D. dianthus is especially useful because it lives a long time, can be dated very precisely through uranium dating, and also shows the variations in carbon-14 (or radiocarbon) due to changing ocean currents. The carbon-14 all originally came from the atmosphere and decays at a precisely known rate, whether it is found in the water itself or in the skeleton of a coral. The less carbon-14 found, the "older" the water. This means that the carbon-14 age of the coral would be "older" than the uranium age of the coral. The larger the age difference, the older the water that bathed the coral in the past.

In a perfectly tame and orderly environment, the deepest water would be the most depleted of carbon-14 because the waters at that depth would have allowed the element the most time to decay. A sampling of carbon-14 content at various depths, therefore, would allow a graph to be constructed, in which the maximum carbon-14 content would be found at the surface.

In the real world, however, the oceans circulate. As a result, an "older" mass of water can actually sit on top of a "younger" mass. What's more, the ways the ocean water circulate are tied to climatic variations. A more realistic graph plotting carbon-14 content against depth would thus be rather wavy, with steeper curves meaning a faster rate of new water flushing in, and flatter curves corresponding to relatively unperturbed water.

The researchers can get this information by cutting up the individual corals and measuring their carbon-14 content. During the animals' 100-year life spans, they take in minerals from the water and use the minerals to build their skeletons. The calcium carbonate fossil we see, then, is a skeleton of an animal that may have just died or may have lived thousands of years ago. But in any case, the skeleton is a 100-year record of how much carbon-14 was washing over the creature's body during its lifetime.

An individual coral can tell a story of the water it lived in because the amount of variation in different parts of the growing skeleton is an indication of the kind of water that was present. If a coral sample shows a big increase in carbon-14 about midway through life, then one can assume that a mass of younger water suddenly bathed the coral. On the other hand, if a huge decrease of carbon-14 is observed, then an older water mass must have suddenly moved in.

A coral with no change in the amount of carbon-14 observed in its skeleton means that things were pretty steady during its 100-year lifetime, but the story may be different for a coral at a different depth, or one that lived at a different time.

In sum, the corals tell how the waters were circulating, which in turn is profoundly linked to climatic change, Adkins explains.

"The last 10,000 years have been relatively warm and stable-perhaps because of the overturning of the deep ocean," he says. "The deep ocean has nearly all the carbon, nearly all the heat, and nearly all the mass of the climate system, so how these giant masses of water have sloshed back and forth is thought to be tied to the period of the glacial cycles."

Details of glaciation can be studied in other ways, but getting a history of water currents is a lot more tricky, Adkins adds. But if the ocean currents themselves are implicated in climatic change, then knowing precisely how the rules work would be a great advancement in the knowledge of our planet.

"These guys provide us with a powerful new way of looking into Earth's climate," he says. "They give us a new way to investigate how the rate of ocean overturning has changed in the past."

Robinson says that the current collection of corals all come from the North Atlantic. Future plans call for an expedition to the area southeast of the southern tip of South America to collect corals. The addition of the second collection would give a more comprehensive picture of the global history of ocean overturning, she says.

In addition to Robinson and Adkins, the other authors of the paper are Lloyd Keigwin of the Woods Hole Oceanographic Institute; John Southon of the University of California at Irvine; Diego Fernandez and Shin-Ling Wang of Caltech; and Dan Scheirer of the U.S. Geological Survey office at Menlo Park.

The Science Express article will be published in a future issue of the journal Science.

Robert Tindol

Caltech, MIT Chemists Look for Better Waysto Use Chemical Bonds to Store Solar Energy

PASADENA, Calif.-With gasoline prices hovering at $3 per gallon, probably few Americans need convincing that another energy crisis is imminent. But what precisely is to be done about our future energy needs is still a puzzle. There's talk about a "hydrogen economy," but hydrogen itself poses some formidable challenges.

The key challenge is, of course, how to make the hydrogen in the first place. The best and cheapest methods currently available involve burning coal or natural gas, which means more greenhouse gases and more pollution. Adopting the cheapest method by using natural gas would merely result in replacing our dependence on foreign oil with a dependence on foreign gas.

"Clearly, one clean way to get hydrogen is by splitting water with sunlight," says Harry Gray, who is the Beckman Professor of Chemistry at the California Institute of Technology.

Gray is involved with several other Caltech and MIT chemists in a research program they call "Powering the Planet." The broadest goal of the project is to "pursue efficient, economical ways to store solar energy in the form of chemical bonds," according to the National Science Foundation (NSF). With a new seed grant from the NSF and the possibility for additional funding after the initial three-year period, the Caltech group says they now have the wherewithal to try out some novel ideas to produce energy cheaply and cleanly.

"Presently, this country spends more money in 10 minutes at the gas pump than it puts into a year of solar-energy research," says Nathan S. Lewis, the Argyros Professor and professor of chemistry. "But the sun provides more energy to the planet in an hour than all the fossil energy consumed worldwide in a year."

The reason that Gray and Lewis advocate the use of solar energy is that no other renewable resource has enough practical potential to provide the world with the energy that it needs. But the sun sets every night, and so use of solar energy on a large scale will necessarily require storing the energy for use upon society's demand, day or night, summer or winter, rain or shine.

As for non-renewable resources, nuclear power plants would do the job, but 10,000 new ones would have to be built. In other words, one new nuclear plant would have to come on-line every other day somewhere in the world for the next 50 years.

The devices used in a simple experiment in the high school chemistry lab to make hydrogen by electrolysis are not currently the cheapest ones to use for mass production. In fact, the tabletop device that breaks water into hydrogen and oxygen is perfectly clean (in other words, no carbon emissions), but it requires a platinum catalyst. And platinum has been selling all year for more than $800 per ounce.

The solution? Find something cheaper than platinum to act as a catalyst. There are other problems, but this is one that the Caltech group is starting to address. In a research article now in press, Associate Professor of Chemistry Jonas Peters and his colleagues demonstrate a way that cobalt can be used for catalysis of hydrogen formation from water.

"This is a good first example for us," says Peters. "A key goal is to try to replace the current state-of-the-art platinum catalyst, which is extremely expensive, with something like cobalt, or even better, iron or nickel. We have to find a way to cheaply make solar-derived fuel if we are to ever really enable widespread use of solar energy as society's main power source."

"It's also a good example because it shows that the NSF grant will get us working together," adds Gray. "This and other research results will involve the joint use of students and postdocs, rather than individual groups going it alone."

In addition to the lab work, the Caltech chemists also have plans to involve other entities outside campus--both for practical and educational reasons. One proposal is to fit out a school so that it will run entirely on solar energy. The initial conversion would likely be done with existing solar panels, but the facility would also serve to provide the researchers with a fairly large-scale "lab" where they can test out new ideas.

"We'd build it so that we could troubleshoot solar converters we're working on," explains Gray.

The ultimate lab goal is to have a "dream machine with no wires in it," Gray says. "We visualize a solar machine with boundary layers, where water comes in, hydrogen goes out one side, and oxygen goes out the other."

Such a machine will require a lot of work and a number of innovations and breakthroughs, but Lewis says the future of the planet depends on moving away from fossil fuels.

"If somebody doesn't figure this out, and fast, we're toast, both literally and practically, due to a growing dependence on foreign oil combined with the increasing projections of global warming."

The NSF grant was formally announced August 11 as a means of funding a new group of chemical bonding centers that will allow research teams to pursue problems in a manner "that's flexible, tolerant of risk, and open to thinking far outside the box." The initial funding to the Caltech and MIT group for the "Powering the Planet" initiative is $1.5 million for three years, with the possibility of $2 to $3 million per year thereafter if the work of the center appears promising.

In addition to Gray, Lewis, and Peters, the other Caltech personnel include Jay Winkler and Bruce Brunschwig, both chemists at Caltech's Beckman Institute. The two faculty members from MIT involved in the initiative are Dan Nocera and Kit Cummins.

Jonas Peters's paper will appear in an upcoming issue of the journal Chemical Communications. In addition to Peters and Lewis, the other authors are Brunschwig, Xile Hu, a postdoctoral researcher in chemistry at Caltech, and Brandi Cossairt, a Caltech undergraduate.


Robert Tindol


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