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Applications

Our project is fundamental in nature. However, some promising applications for our project do exist. One of these applications is the usage of cold resistance as a selection method instead of antibiotics. The more obvious application is the ability to grow bacteria, or other organisms, at lower temperatures. This could be useful for the production of biofuels with a better efficiency. Finally, other iGEM teams could also benefit from our CryoBricks.

Biosynthesis

We consider biosynthesis -- that is, the production of various biological compounds through cell factories -- to be an area of interest, where our project can find many useful applications. Equipping cell factories with CryoBricks and successfully culturing them at lower temperatures may increase their efficiency in three different ways. These relate to the effect of temperature on three different levels: whole cells, enzymes, and the product. Note that while the effect of lowering the temperature can be divided into these levels, actually lowering this temperature is facilitated on the enzyme level, by the proteins encoded in our CryoBricks.
The first level is that of the population and whole cells. Addition of a plasmid containing our CryoBricks may allow cell factories to grow faster at temperatures below their optimum. This may reduce the costs of a production process by saving energy on heating, or it may increase the yield if culturing the cell factories at their optimal growth temperature isn't an option for whatever reason.
The second level is the enzyme level. Certain heat sensitive enzymes can function better at lower temperatures. If a cell factory comprises heat sensitive enzymes, lowering the temperature may increase their kinetic activity. In extreme cases, temperature governs not just the kinetic activity but also the solubility of the enzymes. If the heat sensitive enzymes are involved with the production of the compound of interest, lower temperatures may directly increase its rate of formation or its yield. Alternatively, if the enzyme is involved with cell maintenance or growth, product yield or formation speed may still be influenced indirectly by facilitating a higher cell density or growth rate.
The third scale is that of the product: the biological compound the cell factory is used to produce. Certain products may be unstable, and dropping the temperature can inhibit their rate of degradation by simple thermodynamics. If the product is actively degraded, there is also a chance the decrease in temperature slows down the enzymes that would achieve this. Note that if the product is an enzyme rather than a metabolite, as is the case with many cell factories, thermodynamic degradation won't play much of a role, but inhibiting the proteases that would break them down is all the more valuable.

Biofuel Production

Biofuels are expensive. According to the U.S. Department of Energy's Aquatic Species Program, biodiesel production costs are projected to be at least twice as high as the price of ordinary petroleum diesel, even with very aggressive assumptions about bioproductivity [http://www.nrel.gov/docs/legosti/fy98/24190.pdf [1]]. Currently, over 90% of commercial algae biomass production is done with large-scale open pond systems. There are no feasible alternatives to this setup, because of the high pressure on cost efficiency. Unfortunately, such systems usually suffer from low production rates during the cold season [http://www.nrel.gov/docs/legosti/fy98/24190.pdf ][http://www.futureenergyevents.com/algae/whitepaper/algae_positionpaper.pdf]. Heating the ponds is not an option either, because the energy required for this would cost more than the gained yield brings in.
Following the publication that cyanobacterial strains isolated from high latitudes often remain active at low temperatures [http://www.ffgg.ulaval.ca/paleoecologie/wpcontent/uploads/2011/06/Tang.1997.pdf], Hong et al. (2010) identified the opportunity for cold-resistant cyanobacteria to enhance the efficiency of biofuel synthesis.[http://www.ealgae.kr/Upload/files/ALGAE/PW%EC%B5%9C%EC%A2%85_no6_Alagae25%282%29_10-10up.pdf] If our CryoBricks can be expressed in species other than E. coli, our project might be a humble first step down this road Hong et al. point towards.

Selection

An antibiotic is a compound or substance that slows down growth or kills bacteria. Bacteria can gain resistance for antibiotics by natural selection; if one micro-organism gains this ability it can share this ability through horizontal gene transfer. Although antibiotic resistance is very dangerous for the human health and preventing the spreading of antibiotics is top priority in hospitals, and other medical facility’s, antibiotic resistance is very helpful for research.
When genes are introduced in bacteria, a plasmid is inserted into the bacteria containing this gene and a gene that grand’s antibiotic resistance. By adding antibiotics to the medium or plate, you can select for bacteria that contain this plasmid and therefore your gene of interest.
Our bricks will allow bacteria to grow under a colder environment. When we make a plasmid with our gene instead of an antibiotic, you could use colder temperatures as selecting method instead of antibiotics.
This could be useful as alternative selecting method. If you need a lot of different selecting methods, because it needs to contain different plasmids, or as new selecting method because you don’t want to use expensive antibiotics. University's use a lot of antibiotics as selecting method in the lab. A side effect is that a lot of antibiotics will be flushed through the drain, if our bricks will be used this can be reduced. The brick system of iGEM also works with these kinds of plasmids, so this could be valuable for new iGEM teams.

iGEM teams

Growing bacteria under lower temperatures could help a lot of other iGEM teams. Mostly for teams that have an environmental application, because these environments have in most cases not an optimal temperature for the organism used.

TU Delft 2010

The TU Delft 2010 team attempted to design an E.coli that was able to remove oil from the ocean after an oil spill. For their E.coli to work optimally it has to survive in the harsh conditions of sea water. E.coli cannot normally cope with high salt concentrations and the low temperatures. Our Cryobricks can be used to help E.coli at these lower temperatures.

Brown-Stanford 2011

This year’s Brown-Stanford team is trying to use synthetic biology to allow bacteria to survive in space. As the temperatures in space are a lot lower than 37 °C it could save a lot of energy costs if their bacteria could more easily survive at lower temperatures.

References

1. Sheehan et al. A Look Back at the U.S. Department of Energy’s Aquatic Species Program — Biodiesel from Algae (1998), Executive summary, page 2
2. Benemann 2008 Opportunities and challenges in algae biofuels production
3. Tang et al. (1997) Cyanobacterial dominance of polar freshwater ecosystems
4. Hong et al. (2010) Axenic purification and cultivation of an Arctic cyanobacterium

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