“We call it fishing for electrons.” That’s environmental engineer Craig Criddle describing a new way that he and his colleagues have discovered for generating electricity from sewage.

Wait. What?

Brilliant, right? The Stanford team hopes this breakthrough technology will be used to harvest energy in places such as sewage treatment plants, or to break down organic pollutants in the “dead zones” of lakes and coastal waters where fertilizer runoff and other organic waste can deplete oxygen levels and suffocate marine life.

And this new power all starts with wired microbes. The mini power plants produce electricity as they digest plant and animal waste from wastewater. Right now, still in the laboratory phase, their prototype is about the size of a D-cell battery and looks like a chemistry experiment, with two electrodes, one positive, the other negative, plunged into a bottle of wastewater.

Inside that murky vial, attached to the negative electrode like barnacles to a ship’s hull, an unusual type of bacteria feast on particles of organic waste and produce electricity, which is captured by the battery’s positive electrode.

Scientists have long known of the existence of what they call exoelectrogenic microbes—organisms that evolved in airless environments and developed the ability to react with oxide minerals rather than breathe oxygen as we do, to convert organic nutrients into biological fuel.

Over the past dozen years or so, several research groups have tried various ways to use these microbes as bio-generators, but tapping this energy efficiently has proven challenging. Part of that challenge for the Stanford team is the cost of the oxide minerals necessary to make it happen. “We demonstrated the principle using silver oxide, but silver is too expensive for use at large scale,” says team member Yi Cui. “Though the search is underway for a more practical material, finding a substitute will take time.”

The Stanford engineers estimate that the microbial battery can extract about 30 percent of the potential energy locked up in wastewater. That is roughly the same efficiency at which the best commercially available solar cells convert sunlight into electricity.

Their study was published recently in the Proceedings of the National Academy of Sciences.

Image: Xing Xie, Stanford University

Here’s a round-up of recent science headlines we didn’t want you to miss!

Ancient Rivers

Without a smart phone or GPS device, how did early humans find their way out of Africa? A study published last week in PLoS One determines that ancient rivers, now covered by the Sahara Desert, provided habitable routes to follow.

Simulating paleoclimates in the region, the researchers found evidence of three major river systems that likely existed in North Africa 130,000–100,000 years ago, but are now largely buried by dune systems in the desert. When flowing, these rivers likely provided fertile habitats for animals and vegetation, creating “green corridors” across the region.

“It’s exciting to think that 100,000 years ago there were three huge rivers forcing their way across 1000-km of the Sahara desert to the Mediterranean—and that our ancestors could have walked alongside them,” says lead author Tom Coulthard of the University of Hull, UK.

Cosmic Beginnings?

Did life on Earth hail from Mars, as one researcher proposed last month, or comet collisions? Apparently, in both cases, it all has to do with the chemistry. Carl Zimmer, one of our favorite science writers, has a recent New York Times article about the chemistry needed to produce DNA from RNA. And while it doesn’t look like early Earth had those compounds, Mars might have.

Then, earlier this week, a study published in Nature Geoscience finds that the collision of icy comets with planetary bodies could result in the formation of complex amino acids, the building blocks of proteins (and life).

The researchers suggest that this process provides another piece to the puzzle of how life was kick-started on Earth, after a period of time between 4.5 and 3.8 billion years ago when the planet was being bombarded by comets and meteorites.

The team made their discovery by recreating the impact of a comet by firing projectiles through a large high-speed gun. This gun, located at the University of Kent, uses compressed gas to propel projectiles at speeds of 7.15 kilometers per second into targets of ice mixtures, which have a similar composition to comets. The resulting impact created amino acids such as glycine and D- and L-alanine. Sounds like a fun method of discovery…

Speaking of fun collisions, if you want more of them, the Morrison Planetarium at the Academy is featuring Cosmic Collisions in its current show rotation. From the our website:

Creative and destructive, dynamic and dazzling, collisions are a key mechanism in the evolution of the Universe.

Missing Mars Methane

One chemical Mars seems to be missing? Methane. The gas was sought as a possible sign of microbial life currently living on the seemingly barren world. However, despite earlier reports that NASA’s Mars rover, Curiosity, discovered methane on the red planet, NASA reports today in Science that none has been found.

Curiosity’s earlier evidence of methane detection turned out to be within leftover air from Earth. And previous reports of localized methane concentrations up to 45 parts per billion on Mars were based on observations from Earth and from orbit around Mars.

“It would have been exciting to find methane, but we have high confidence in our measurements,” says the report’s lead author, Chris Webster. “We measured repeatedly from Martian spring to late summer, but with no detection of methane.”

But don’t give up on microbial Martians just yet… “This important result will help direct our efforts to examine the possibility of life on Mars,” says NASA’s Michael Meyer. “It reduces the probability of current methane-producing Martian microbes, but this addresses only one type of microbial metabolism. As we know, there are many types of terrestrial microbes that don’t generate methane.”

Looking for extraterrestrial life? Next month’s Brilliant!Science festival can deliver it to you. Visit this page for more information.

Image: the Tunable Laser Spectrometer on-board Curiosity: NASA/JPL-Caltech

As scientists understand more about microbes, it seems that the miniscule life forms have the potential to contribute to a host of useful activities—making biofuels, fighting human disease, improving high tech, you name it!

Now, a feature article in the September issue of Scientific American looks at how soil microbes could revolutionize agriculture.

Soil microbes include everything from bacteria to fungi, and article author Richard Conniff likes to call the lot collectively “the agribiome.” These microscopic life forms have the potential to solve many crises facing agriculture today—everything from climate change and drought to Salmonella and other food-bourn illnesses, from the costs of man-made fertilizers to the GMO controversy.

Conniff’s article comes on the heels two other papers that highlight the importance of soil microbes. In a paper published last week in the Proceedings of the National Academy of Sciences, a team of British scientists emphasizes how important soil microbe diversity is for European crops. And two weeks ago, American researchers determined that soil microbes are responsible for controlling carbon in the soil—an important factor in retaining the important mineral in the dirt as temperatures rise and the climate warms.

The Scientific American article gives many examples of these crucial, unseen microbial workers. Bacteria found in soil on the United States West Coast can kill Salmonella, Conniff reports, so the USDA is looking at introducing the bacteria in East Coast soils to stop the occasionally deadly outbreaks.

And instead of genetically modifying actual crops to withstand drought conditions, Mexican scientists are looking at modifying bacteria to strengthen the plants in the soil at their roots.

Mycorrhizal fungi in the soil are heroes in both the SciAm article and the PNAS study. The fungi deliver much-needed phosphate to crops, an easier and cheaper way to get the important mineral to the plants to help them grow. Artificial fertilizers can be expensive, especially for farmers in developing countries, and harm the natural soil ecosystem. Run-off from these fertilizers also contaminates freshwater and marine environments. A simple animation of how the fungi works to help plants is available here.

(Mycorrhizal fungi also play a heroic role in the next Academy planetarium show! Currently in production and set for a fall 2014 opening date, the latest production from our visualization studio will highlight the complex relationships in ecosystems—and how humans fit into the picture.)

If farmers and scientists can acknowledge that collaborating with microbes can play a crucial role in farming, “we will have come a step closer to feeding a hungry world,” Conniff concludes.

The lead author of the PNAS paper, Franciska de Vries, says, “This research highlights the importance of soil organisms and demonstrates that there is a whole world beneath our feet, inhabited by small creatures that we can’t even see most of the time. By liberating nitrogen for plant growth and locking up carbon in the soil they play an important role in supporting life on Earth.”

Mycorrhizal fungi image: Nilsson et al. BMC Bioinformatics

Oh, is that all?

Cameron is not a scientist, but a proponent of science, as he described at a press conference yesterday. (And scientists need more people like him on their side!) In this role, he hopes to bring science into the popular dialogue and provide tools to scientists—whether that’s funding (through different sources including his Blue Planet Marine Research foundation) or engineering (such as his Deepsea Challenger submersible).

This past March, Cameron and a team of scientists headed to the Mariana Trench in the Pacific Ocean. Using his submersible as well as two unmanned landers, Cameron gradually dove deeper and deeper into the Mariana Trench, collecting samples and video for scientists.

At the AGU meeting, researchers described their findings at these depths and locations. Kevin Hand, an astrobiologist with NASA’s Jet Propulsion Laboratory, spoke of microbial mats and the serpentinization that he witnessed. Doug Bartlett, a microbiologist from Scripps Institution of Oceanography at UC San Diego, discussed not only the many novel microbes discovered, but also the larger organisms found at some of these depths, including crustaceans, worms, corals and anemones. Patricia Fryer, a geologist from the University of Hawaii, described the tectonic plates, subduction zone and topography at that location.

Together, the findings describe a rich and unique ecosystem. With no other resources to feed the microbes, the researchers propose that the serpentinization on the overriding subduction plate is the energy source for microbes and microbial mats at those depths. Those microbes in turn feed the larger animals seen in the area.

Cameron and the scientists go a step further, suggesting that the serpentinization’s match of geochemistry and biochemistry could be how life began on this planet. And what’s more, this could be how life works in other water bodies in our Solar System and beyond. Cameron named the moons Enceladus, Europa and Callisto as potentially harboring these processes.

We have much to learn about this unusual spot on our planet, 35,630 feet below sea level, and Cameron’s quest is a boon for marine science. Even though the proposed theories about the origin of life seem a bit premature, just focusing on the “unexplored frontiers right here on Earth,” in Cameron’s words, is enough. Isn’t it?

Image: Kmusser/Wikipedia using NOAA data

]]> http://www.calacademy.org/sciencetoday/diving-deep-for-science/559483/feed/ 0 http://www.calacademy.org/sciencetoday/antarctic-lake-life/559419/ http://www.calacademy.org/sciencetoday/antarctic-lake-life/559419/#comments Wed, 28 Nov 2012 19:52:54 +0000 molly http://www.calacademy.org/sciencetoday/?p=9419 Think you have it tough in this winter environment? Think again, buddy.

What if you lived in a saltwater lake that was six times saltier than the ocean, and the water was buried under nearly 20 meters (65 feet) of ice? The temperature is a brisk -13°C and oh yeah, we forgot to mention that the lake lacks oxygen and contains high levels of organic carbon.

Sounds pleasant, right? You’re probably thinking nothing can live there. Wrong.

Lake Vida in Antarctica isn’t exactly teeming with life, but life does exist in its harsh environment. Diverse life, in fact. At least eight new species of bacteria call Lake Vida home according to a new study in the Proceedings of the National Academy of Sciences.

Researchers from the University of Illinois and the Desert Research Institute took samples from the lake in 2005 and 2010, using stringent protocols to avoid contaminating the pristine ecosystem. Scientists estimate that this lake has been isolated from outside influences (including the Sun’s energy!) for almost 3,000 years.

“This study provides a window into one of the most unique ecosystems on Earth,” says lead author Alison Murray. “[It] expands our understanding of the types of life that can survive in these isolated, cryoecosystems and how different strategies may be used to exist in such challenging environments.”

Strategies like food-supply. The researchers have a theory: “Geochemical analyses suggest that chemical reactions between the brine and the underlying sediment generate nitrous oxide and molecular hydrogen,” says co-author Fabien Kenig. “The hydrogen may provide some of the energy needed to support microbes.”

“If that’s the case,” says Murray, “This gives us an entirely new framework for thinking of how life can be supported in cryoecosystems on Earth and in other icy worlds of the Universe.” Think Mars or Europa, says New Scientist.

And also think Vostok and Ellsworth—two more Antarctic lakes that have been isolated millions of years longer than Vida. Scientists are studying those lakes this Antarctic summer. Perhaps they will find life in these harsh conditions, as well?

Image: Peter Glenday, University of Illinois

Uncovering the human microbiome represents a new frontier in science. Thanks to new technology, we’re beginning to understand what these microscopic organisms do, how they do it, and why they exist inside of us.

Last Friday, the awesome Bay Area Science Festival presented “Gut Check: The Hidden World of Microbes.” The panel included two UC San Francisco researchers—our friend, Joe DeRisi, and Michael Fischbach—and science writer extraordinaire, Carl Zimmer. If you follow Zimmer’s Discover blog, The Loom, you know that he loves anything tiny and gross—parasites, bacteria, fungus, the like—so we knew it would be a juicy discussion.

DeRisi developed the ViroChip—a technology that allows scientists to scan samples for several different viruses—over 10,000 things at a time—and bacteria, fungi, and parasites. When Fischbach looks at us, he sees the 100 trillion microorganisms living inside us. These microorganisms make up 10% of our genes, so he uses genome-sequencing technology to study all of them at once.

The following are some of the topics discussed by the panel:

Antibiotics and other Good Bacteria

Fischbach got into human microbiome research looking for drugs. Your gut (and skin and oral) bacteria are natural antibiotics and statins (cholesterol-lowering drugs). They could also possibly control obesity and diabetes. Microbes support your immune system and metabolism, and many of the bacteria in your gut create neurotransmitters, fueling research about how our gut bacteria affect our brains.

Fischbach pointed out how current antibiotics take a “carpet bomb” approach—killing all bacteria in our bodies, good and bad. With more research, he believes that specific good bacteria could target specific bad bacteria—taking a more “scalpel” approach to antibiotics.

Tending the Garden

Among the microorganisms in our body, there are those that help us digest food and create energy and those that just feed themselves. Insoluble fiber may keep us healthy, but we’re not actually absorbing any of it—the microbes keep it all to themselves! As Zimmer said, “You’re not eating it for yourself, but rather tending the garden.” The garden of gut flora.

The Virome

Did you know we have seven trillion viruses in our body when we’re healthy? Some of these viruses attack us and some attack other viruses or bacteria. And, are you ready for this? DeRisi can’t “think of any example of a beneficial virus.” So what are they all doing there? DeRisi has no clue, and every time he sequences he finds new viruses, wondering what role they might play.  Bringing up the question, is there a virome in addition to the biome of the human body?

With trillions of viruses and new ones evolving, does DeRisi lay awake at night in a panic? No. (Phew!)

So whether riding BART or keeping your child in a germ-free environment, the message of the panel was don’t worry about these tiny organisms (at least, for now). More research is needed to find out exactly what kind of tug of war is going on inside of our bodies.

The animals are built like carnivores, too. A genomic study on the wild panda in 2009 proved that that the bears have none of the features that other herbivores (like cows) have to breakdown the tough cellulose fibers of bamboo.

In fact, of the 12.5 kg (27.5 lbs) of bamboo the pandas eat in a day, they’re only able to digest about 17% of it. According to National Geographic News:

This explains why pandas also evolved a sluggish, energy-conserving lifestyle.

Scientists from the Chinese Academy of Sciences decided to look at the microorganisms that live in the guts of these bears. So they grabbed some panda poop, or, rather, stool samples from seven wild pandas and eight captive pandas. (Their diets vary a bit.)

Analyzing the samples, the researchers found 13 different types of Clostridium-related bacteria, known to breakdown cellulose. Of those, seven were unique to the pandas compared to other mammals. The researchers conclude that these microbes allow the panda to gain extra energy from the bamboo stalks.

Nature News describes this extraordinary feat in context:

These microbes are part of a suite of evolutionary adaptations — alongside powerful jaws and teeth, and pseudo-thumbs, bones that allow them to grip plant stalks — that help pandas to live on bamboo, despite having a carnivore’s digestive system.

The new research is published in this week’s Proceedings of the National Academy of Sciences.

Image: Mfield, Matthew Field/Wikipedia

Researchers from the University of Alberta found that billions of years before life evolved in the oceans, thin layers of microbial matter in shallow water produced enough oxygen to support tiny, mobile life forms.

Science News puts it eloquently:

Such clumps of oxygen-producing gunk could have supplied the first mobile animals with food to eat and air to breathe.

The researchers say worm-like creatures could have lived on the oxygen produced by photosynthetic microbial material, even though oxygen concentrations in the surrounding water were not high enough to support life. The research was conducted in shallow lagoons in Venezuela where the high salt content is comparable to oceans older than 500 million years.

The link between biomats and animals is demonstrated by the trace-fossil record, which are tracks left behind by the movements of the worm-like creatures. The trace-fossil records for these animals date to at least 555 million years ago when oxygen levels would have been a tenth of what they are now.

These findings suggest that the appearance of animals was not dependent on an oxygenated ocean. Rather, the earliest animals could have lived within photosynthetic biomats and derived life-sustaining oxygen from that source.

The researchers say their work opens the door to the search for life in early periods of Earth’s history when it was believed there was absolutely no oxygen and no chance of finding life.

Image: Stefan Lalonde

The squid are part of an experiment to see if, like some collegiate females on spring break, good bacteria “go wild” in the microgravity of space. Bobtail squid use bacteria called Vibrio fischeri to generate light. According to Discovery News:

That light helps the squid hunt for prey in dark waters. It also provides camouflage from any organisms trying to eat him, because the squid doesn’t cast a telltale shadow on the ocean floor as a result of the moon’s rays shining down into the water.

Previous shuttle experiments have shown what happens to harmful bacteria in space, but this will be the first experiment with beneficial bacteria.  Scientists are hoping that these results with squid will translate to beneficial bacteria with humans.

The NASA press kit reports that worms are part of the mission:

One NASA experiment known as Biology (Bio) will use, among other items, C. elegans worms, that are descendants of worms that survived the STS-107 space shuttle Columbia accident.

Haven’t these worms been through enough?!

Wired UK has a breakdown of other microbes joining STS134:

The microbes on-board Endeavour include the tardigrades (nicknamed Water Bears) which are large extremophiles that can withstand temperatures as biting as absolute zero, and as hot as 150 degrees Celsius. They’re joined by the Deinococcus radiodurans (which NASA dubbed “Conan the Bacterium“) which can survive upward of 15,000 Gy of radiation — 10 Gy is more than enough to kill an average human.

Haloarcula marismortui (Old Salty) loves salt, and lives in levels of high salinity that would kill other organisms. Pyrococcus furiosus (Fire Eater) is all about heat, and thrives in temperatures over 100 degrees Celsius. Cupriavidus metallidurans (which doesn’t have a nickname, unfortunately) plays a vital role in the formation of gold nuggets, thanks to its love of gold tetrachloride: a compound that is toxic to most other microorganisms.

Finally there’s Bacillus subtilis (The Average Joe), which is a model organism used in hundreds of biological experiments. It’s been into space many times before, so it’ll be a good comparison point for other studies.

You know, Dorothy only had lions and tigers and bears to face in Oz…

Image by Hans Hillewaert/Wikimedia