Season 3, Episode 2: Dust in the Wind
Back at NorBAC, David and Bob test positive for cyanobacteria infection, which they brought back from Utah. Bob hypothesizes that the cyanobacteria is splitting all the water in their cells to make hydrogen, running on electricity generated by another bacterium, geobacter. The race is on to try to counteract the infection and stop the bacterial chain reaction.
 Image provided courtesy of Shaftesbury Films. |
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David, Bob and Mayko discussing how geobacter might be providing energy for the nano-engineered cyanobacteria. |
IS IT POSSIBLE TO DESIGN A VIRUS TO ATTACK BACTERIA AND STOP AN INFECTION?
How do viruses infect bacteria?
 Image provided courtesy of AXS Studio Inc and Shaftesbury Films. |
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The 'nanopredator' is an engineered bacteriophage virus. Here we see it infecting its host -- a cyanobacterium. |
Generally, one virus only infects one species. This is why when you have a cold you can’t pass it to your dog. Human cold viruses infect only humans. Likewise, you can’t catch your dog’s kennel cough. There are some viruses, however, that can infect multiple species, like the rabies virus, which can infect all mammals. Also, there are viruses that infect only bacteria.
Viruses are composed of genetic material wrapped in a protein shell. Some of the proteins on the viral shell recognize and attach to proteins on the cell the virus is able to infect. Once the virus recognizes the cell, it latches on and puts its genetic material inside the cell. Once inside, the virus hijacks the cell’s machinery to make more virus by making the proteins encoded in the virus’ genetic material, as well as more copies of the genetic material. The new genetic material is packaged in the new proteins, and a new virus is born! The newly made virus exits the cell to infect other cells.
Eventually the cyanobacterium is lysed by hordes of newly-formed virus particles itching to get out and start the process anew.
 Image provided courtesy of AXS Studio Inc and Shaftesbury Films. |
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How does one design a virus?
One can alter the genetic material within the virus to make different proteins or slightly change or mutate the natural viral proteins. Using molecular techniques it also is possible to swap in genes from other organisms into a virus.
So…
Armed with information about which proteins on the bacteria’s surface the virus latches onto and which viral proteins are required for doing the latching, it might be possible to design a virus that infects specific bacteria. However, it probably would take much longer than this episode portrayed.
IS IT PROBABLE THAT TWO DIFFERENT BACTERIA WOULD INFECT AND ESTABLISH A SYNTROPHIC RELATIONSHIP IN A HOST?
Cyanobacteria (green) are able to convert water to hydrogen and oxygen using energy from sunlight. In the absence of sunlight, geobacter (brown) provide the energy.
 Image provided courtesy of AXS Studio Inc and Shaftesbury Films. |
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What are Geobacter?
Geobacter are a type of bacteria that can harvest electrical energy from organic matter. Just as our cells need oxygen to break down sugar for energy, Geobacter use iron oxides—rust—to break down organic compounds for energy. They can transfer the energy they make into specially designed wires and generate a weak current. For this reason, Geobacter are under intensive study for their potential use in generating alternative energy and as the power behind microbial fuel cells, known as MFCs.
What is a syntrophic relationship?
Syntrophy occurs when one or more species live(s) off of another species. Usually one survives on something the other makes. An example of a syntrophic relationship is that of the dung beetle and cow—dung beetles eat and survive on cow feces.
 Image provided courtesy of AXS Studio Inc and Shaftesbury Films. |
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Together they are unstoppable! |
So…
In order for Geobacter and the engineered, light-independent cyanobacteria to establish a syntrophic relationship in a person, at least two things must be true: First, both bacteria need to survive the onslaught of the human immune system, which protects the body against invasion by bacteria, viruses, etc., and second, in the unlikely event they avoid destruction by the immune system, they need to “live” in close proximity for the Geobacter to pass electrical energy to the cyanobacteria.
People do have syntrophic relationships with bacteria, but they are helpful, rather than harmful. For example, Vitamin K is essential for blood and blood vessel health and is made by certain types of E. coli bacteria living in human intestine.
- by Audrey M. Huang, Ph.D.
Want to read and learn more?
To learn more about viral infection, visit:
http://www.hhmi.org/biointeractive/animations/infection/inf_frames.htm
To learn more about geobacter, visit:
http://www.geobacter.org/
To read more about vitamin K, visit:
http://en.wikipedia.org/wiki/Vitamin_K
