Design: Conversion of carbon monoxide
Carbon monoxide is often referred to as the silent killer. It is a colorless odorless gas
that can be lethal if enough of it is inhaled. This toxic gas takes the lives of over 400 Americans
each year, and over 4,000 are hospitalized. When carbon monoxide is inhaled it quickly
attaches to the red blood cells, preventing oxygen from attaching. This causes a major lack of
oxygen throughout the body. Symptoms of carbon monoxide poisoning include headache,
dizziness, weakness, nausea, vomiting, chest pain, and confusion. If the carbon monoxide is
present in higher concentrations it may result in loss of consciousness or death.
Not only does carbon monoxide have lethal effects on the human body, it also
contributes to global warming. When carbon monoxide is released into the atmosphere it reacts
with hydroxyl radicals (OH). As the amount of hydroxyl radicals decreases the lifetimes of
stronger greenhouse gases, like methane, increases so they impact our atmosphere for much
longer than they should.
The main way of combatting carbon monoxide poisoning in homes is to have a carbon
monoxide detector. About 15-20 percent of all American homes have carbon monoxide
detectors. The detectors can cost up to 200 dollars so it is obvious why the average household
may be deterred from investing in one. The design of the detector is also not quite foolproof.
Imagine a scenario where a family is sleeping peacefully on a winter night, unaware that their
house is filling with carbon monoxide. Even if the alarm goes off the family may not hear it, or
they may have already have inhaled enough CO to make them too weak to get their whole
family out in time. What they need in this situation is something that quickly starts reducing the
levels of carbon monoxide throughout the house. One way to accomplish this would be to
engineer a bacteria that metabolizes the carbon monoxide converting it into safer components.
Carbon monoxide dehydrogenase is an enzyme that can easily convert carbon
monoxide. It does this by inducing this reaction:
H2O + CO + A = CO2 + AH2
A in this equation stands for aldehyde. Aldehydes are compounds made up of a carbon,
oxygen, hydrogen, and a formyl group. They are commonly associated with fragrances in foods.
The genes that code for this enzyme are cdhA and cdh. This gene would be inserted into
E-coli bacteria. However there should be an AND gate before the promoter to this gene. This
truth table displays how the AND gate would work in the E Coli:
CO
H2O
A
cdhA, cdhB
1
0
0
0
0
1
0
0
0
0
1
0
1
1
1
1
The gene would only be activated if all three components of the reaction are present.
Without all three parts the carbon monoxide dehydrogenase would be useless. This flowchart
represents the overall function of the bacteria:
The newly engineered E-coli could be utilized in a unique type of mist machine. This
device would resemble a fire sprinkle on the ceiling. It would be loaded with water, an aldehyde
and colonies of the E-coli. One potential aldehyde to use is vanillin, which is the primary
component in vanilla bean extract. The device would be triggered by your average carbon
monoxide detector causing the device to release a mist of water vapor, vanillin, and bacteria.
Not only will the mist have a sweet vanilla aroma, it will also remove the carbon monoxide from
the environment potentially saving lives.
Unfortunately, there are some potential problems with this product. Firstly, the bacteria probably
won't have a very long shelf life so there would have to be something in the device to keep the colonies
alive. Furthermore, it is unknown if the AH2 product will be safe. Finally, it is likely that some people will
have allergies to either the E-coli or the vanillin. Obviously this product isn't quite ready for sale however it
does have the potential to save lives or at least trips to the ER.
Sources:
1. "Acetate Biosynthesis by Acetogenic Bacteria. Evidence That Carbon Monoxide Dehydrogenase Is the
Condensing Enzyme That Catalyzes the Final Steps of the Synthesis." Acetate Biosynthesis by Acetogenic
Bacteria. Evidence That Carbon Monoxide Dehydrogenase Is the Condensing Enzyme That Catalyzes the
Final Steps of the Synthesis. N.p., n.d. Web. 02 Aug. 2013. <http://www.jbc.org/content/260/7/3970.short>.
2. "Aldehyde." Wikipedia. Wikimedia Foundation, 31 July 2013. Web. 02 Aug. 2013.
<http://en.wikipedia.org/wiki/Aldehyde>.
3. "Aldehydes and Ketones." Aldehydes and Ketones. N.p., n.d. Web. 02 Aug. 2013.
<http://chemed.chem.purdue.edu/genchem/topicreview/bp/2organic/aldehyde.html>.
4. "Anaerobic Carbon Monoxide Dehydrogenase Diversity in the Homoacetogenic Hindgut Microbial
Communities of Lower Termites and the Wood Roach."PLOS ONE:. N.p., n.d. Web. 02 Aug. 2013.
<http://www.plosone.org/article/info:doi/10.1371/journal.pone.0019316>.
5. "Carbon Monoxide Dehydrogenase." Wikipedia. Wikimedia Foundation, 31 July 2013. Web. 02 Aug. 2013.
<http://en.wikipedia.org/wiki/Carbon_monoxide_dehydrogenase>.
6. "Result Filters." National Center for Biotechnology Information. U.S. National Library of Medicine, n.d.
Web. 02 Aug. 2013. <http://www.ncbi.nlm.nih.gov/pubmed/18401137>.
7. http://www.jbc.org/content/266/11/6883.full.pdf