Mood:  special

How bacteria could help power the future

Organisms could get energy through chemical reaction releasing hydrogen

By Michael Schirber

updated 12:05 p.m. ET Aug. 27, 2008

Hydrogen is the cleanest and most abundant fuel there is, but extracting it from water or organic material is currently not a very efficient process. Scientists are therefore studying certain bacteria that exhale hydrogen as part of their normal metabolism.

"The production of hydrogen by microorganisms is intimately linked to their cellular processes, which must be understood to optimize bioenergy yields," said Amy VanFossen of North Carolina State University.

Of particular interest are microbes that thrive in hot temperatures, near the boiling point of water. VanFossen and her colleagues carried out a detailed DNA study of one of these thermophilic (heat-loving) bacteria called Caldicellulosiruptor saccharolyticus, which was first found in a hot spring in New Zealand.

The results, presented last week at the American Chemical Society meeting in Philadelphia, indicate which genes allow C. saccharolyticus to eat plant material, referred to as biomass, and expel hydrogen in the process.

Fuel cell vehicles are starting to be available for lease in California and the New York area. They run off of hydrogen gas and emit only water vapor out the tail pipe.

Hydrogen can be found everywhere: it's the "H" in H2O and a major element in biological processes. The problem is that it takes quite a bit of energy to separate the hydrogen from the molecules it is found in.

However, certain organisms, such as the bacteria in cow stomachs , get energy from food through a chemical reaction that releases hydrogen gas. Often this hydrogen is immediately taken up by other bacteria, called methanogens , that convert it to methane .

One of the challenges, therefore, of producing hydrogen from bacteria is to prevent the methanogens from gobbling up the gas. The advantage of thermophiles is that they operate at temperatures that are typically too hot for methanogens. C. saccharolyticus, for example, prefers a toasty 160 degrees Fahrenheit (70 degrees Celsius).

Furthermore, the chemistry of hydrogen formation is easier at these higher temperatures, said Servé Kengen from Wageningen University in the Netherlands.

"In general, thermophiles have a simpler fermentation pattern compared to [lower temperature] mesophiles, resulting in fewer byproducts," he said.

Bionic microbe
Kengen is part of a European Union project called Hyvolution, which is developing decentralized hydrogen production that can be performed near where biomass is grown.

"Biological hydrogen production is well suited for decentralized energy production," Kengen said. "The process is performed at almost ambient temperature and pressure, and therefore it is expected to be less energy intensive than thermochemical or electrochemical production methods [which are alternative ways to get hydrogen]."

Kengen said that C. saccharolyticus, or what he calls "Caldi," is very attractive for this application. It is unique in that it eats a wide range of plant materials, including cellulose , and can digest different sugars (technically carbohydrates) at the same time.

Mood:  bright

Songbird's duets not so harmonious

Researchers say bird couples sing duets to protect territories

	Some birds, such as the rufous-and-white wren pictured here, fight by singing, using melodic tweets to defend their relationships and territories  View related photos
Daniel Mennill

Discovery.com

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By Jennifer Viegas

updated 12:33 p.m. ET Sept. 4, 2008

Harmonious bird songs may sound pleasant to people, but a new study has found that at least some birds fight by singing, using melodic tweets to defend their relationships and territories.

The study, published in the latest issue of Current Biology, was made possible by eight microphones positioned strategically throughout the dense tropical forests of Costa Rica. The microphones fed the song duets of rufous-and-white wrens into a single laptop computer, enabling researchers to pinpoint the exact positions of the colorful songbirds.

"The first time I heard a rufous-and-white wren song, I was completely captivated by its voice," lead author Daniel Mennill told Discovery News. "They have low-pitched, flute-like sounds that are really quite beautiful."

Mennill, an associate professor in the Department of Biological Sciences at the University of Windsor, and colleague Sandra Vehrencamp conducted two experiments on breeding pairs of the birds, which can sing such closely matched duets that human listeners think they're hearing a solo performance.

They first recorded the birds in a passive context.

"This is analogous to recording you as you go about your daily routine of making your lunch, tidying your house, etc.," explained Mennill.

The bird pairs used duets to find each other, like a romantic B movie where the male and female stars sing out to one another while moving ever closer. Given the density of the birds' forest home, such singing is one of the few ways males and females can find each other.

For the second experiment, the scientists recorded the birds in a more aggressive context. Using loudspeakers, they simulated the voices of a rival pair.

"This is analogous to recording you if you were reacting to a burglar breaking into your house," Mennill said.

When a bird pair would hear a rival couple singing, the "birds' duet rates skyrocketed."

The listening couple "duetted intensely and approached the loudspeakers aggressively," Mennill said, with males singing loudly and forcefully when they heard a rival male tweet.

The researchers believe the bird couples sing duets to not only protect their territories from rival couples, but also to prevent other birds from disrupting their relationship. Extra-pair matings have been documented in this species and most other birds.

"Moreover, rufous-and-white wrens frequently engage in divorce," the authors point out.

They believe their findings apply to many other birds that sing duets, particularly those living in areas of thick vegetation.