Season 3, Episode 1: A Spontaneous Moment
Six scientists are killed when the top-secret Greenway lab in Utah explodes and NorBAC is sent to investigate. The scientists appear to have spontaneously combusted from the inside out! David and Bob find a cold room full of cyanobacteria that apparently had been engineered to contain “nano-dots,” which could hold the key to understanding what happened.
 Image provided courtesy of AXS Studio Inc and Shaftesbury Films. |
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At extreme magnification, we see that the surface of the cyanobacterium is peppered with nano-dots. We’re dealing with "customized pond scum". |
IS IT POSSIBLE TO ENGINEER CYANOBACTERIA TO MAKE THEIR OWN ENERGY RATHER THAN CAPTURE IT FROM THE SUN?
What are cyanobacteria?
 Image provided courtesy of AXS Studio Inc and Shaftesbury Films. |
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Artist’s rendition of an electron micrograph of cyanobacteria. |
At this magnification, everything looks normal.
Cyanobacteria are single-celled organisms that live in waterways like rivers and streams and can make their own food. Although most are microscopic, some live in colonies big enough see. They are often called blue-green algae, but that term is inaccurate because algae are closely related to plants whereas cyanobacteria, as the name suggests, are more closely related to bacteria.
Cyanobacteria make their own food by photosynthesis—collecting energy from the sun to convert carbon dioxide and water into a sugar called glucose. Photosynthesis also produces a byproduct – the oxygen in the air we breathe.
Can electricity substitute for the sun’s energy in photosynthesis?
In photosynthesis, special proteins in the cell basically capture and translate the sun’s energy—light energy—into electrical energy. When light with a specific intensity hits these special proteins, it excites an electron, which has a negative charge. The excited electron is passed to other proteins where its energy is used to drive the chemical reactions that turn water and carbon dioxide into sugar. Eventually, all extra energy is sapped from the excited electron and it returns to its original state, ready to be excited by light all over again. If a jolt of electricity could be given to a cell to excite only that one electron without damaging the rest of the cell, it might be possible to substitute electricity for sun energy in photosynthesis.
Can cells generate electricity?
Yes. For example, nerve cells transmit information from one cell to another through tiny electrical pulses, which they generate by altering how much salt is inside versus outside the cell. However, these electrical pulses affect the whole cell and larger compartments within cells. They are not targeted to one specific protein like the one that holds the excitable electron for capturing light energy during photosynthesis.
So…
The science is not quite at the point where cyanobacteria can be engineered to make their own electrical energy and forego the sun. However, researchers recently have used nanotechnology to generate electrical currents to activate nerve cells. Light-independent cyanobacteria may not be too far off.
IS IT PROBABLE TO USE CELLS TO MAKE HYDROGEN FOR ALTERNATIVE ENERGY?
How could hydrogen be used as an alternative energy source?
One use of hydrogen is as a fuel replacement for cars and other motors. Unlike fossil fuels—gasoline, oil, coal—hydrogen burns cleanly, generating only water vapor as a byproduct. Hydrogen fuel would reduce smog-causing harmful emissions and improve air quality.
 Image provided courtesy of AXS Studio Inc and Shaftesbury Films. |
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Cyanobacteria produce small amounts of hydrogen as part of their daily existence. |
However, hydrogen has its own challenges. In its pure form hydrogen is very flammable. It’s a very light gas that floats away easily, making it hard to capture and collect in pure form. It is possible to make hydrogen by using electricity to split water into hydrogen and oxygen. But performing this chemical reaction uses more energy than it yields. Using hydrogen as an alternative energy source will require scientists to develop energy-efficient means to make and store it.
Can cells make their own hydrogen?
Some cells can make hydrogen, but it uses a lot of energy and generally occurs only when there is no oxygen present. When there isn’t much available oxygen, certain cells do what’s called anaerobic respiration where they break down sugars to make energy to power chemical reactions that keep them alive. One example of anaerobic respiration is fermentation, where yeast cells eat sugar to make energy and release alcohol as a by-product.
The problem with anaerobic processes is they aren’t very efficient and don’t yield much product or by-product. However, this is an active area of research and some teams have discovered ways to get bacteria to make up to four times their normal hydrogen output by shocking the bacteria with a bit of electricity.
So…
Although the research is not quite there yet, it might just happen some day that researchers will devise so-called microbial fuel cells to generate enough hydrogen to power your car. Instead of filling it with gasoline, you may just have to feed the bacteria.
- by Audrey M. Huang, Ph.D.
Want to read and learn more?
To learn more about cyanobacteria, visit:
http://www.ucmp.berkeley.edu/bacteria/cyanointro.html
To learn more about how scientists are using nanotechnology to electrically stimulate cells, visit:
http://nanotechwire.com/news.asp?nid=4384
To learn more about photosynthesis and the electron transport chain, visit:
http://en.wikipedia.org/wiki/Photosynthesis
To learn more about microbial fuel cells designed to make hydrogen, visit:
http://live.psu.edu/story/11709
