Applications

Because of the fundamental nature of our project, there's only a few applications in which it can be put to direct use. One we shall investigate is the possibility of using cold resistance instead of antibiotic resistance as a selective property. Perhaps of greater interest than the direct applications, however, are the more general fields of science and industry in which our CryoBricks may be exploited. One such field we take particular interest in, is that of biosynthesis. Another application we feel needs to be mentionned is that many other iGEM projects, both past and present, may benefit from ours. These projects are discussed seperately on our collaboration page.

Cold vs. Antibiotics

Ever since Gerhard Domagk developed the first commercially available antibiotic - Prontosil, for which he won 1939's Nobel Prize in Medicine - these chemicals have been very prevalent in clinical therapy. While treatment with antibiotics is for the most part very effective, unfortunately, it tends not to be very sustainable.[1] As antibiotics get used more and more, so do their targets develop resistances more and more. At the time of this writing (August 2011), the Beth Shalom hospital in Amstelveen is struggling with an outbreak of MRSA (multiple resistant Staphylococcus aureus), and only weeks before, the Maasstad ziekenhuis in Rotterdam suffered from an outbreak of multiple resistant Klebsiella.

Because of these indirect risks to the population's health inherent to large scale application of antibiotics, the clinical environment has been making efforts to mitigate these risks for a long time. Attempts have been (and are being) made to enhance the efficiency of antibiotic treatments while minimizing the chances of pathogens developping new resistances. So far, this effort appears to be fruitful.[2] Inspired by this success, our team feels it may also be beneficial to reduce the need for antibiotics in the academic environment.

[Discuss why reducing antibiotic use in labs is also useful here]
- Less of a risk when bacteria comprising antibiotic-resistance plasmids leave the lab in an uncontrolled manner
- Practical conveniences
  - No more need to prepare selective plates or media
  - Able to culture plates over the weekend without overcrowding
- ???

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 succesfully 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 inhibitting the proteases that would break them down is all the more valuable.

Example 1: 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.[3] 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.[3][4] 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[5], Hong et al. (2010) identified the opportunity for cold-resistant cyanobacteria to enhance the efficiency of biofuel synthesis.[6] If our CryoBricks can be heterologously expressed in species other than E. coli, our project might be a humble first step down this road Hong et al. point towards.

Example 2: Heterologous Expression of Ethylene Forming Enzyme and Acetoin Reductase

[Under construction] Don't forget to make links out of the [#] references!

References

M Millar, Can antibiotic use be both just and sustainable... or only more or less so?
Rattanaumpawan, Sutha and Thamlikitkul - Effectiveness of drug use evaluation and antibiotic authorization on patients' clinical outcomes, antibiotic consumption, and antibiotic expenditures
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
Benemann 2008 Opportunities and challenges in algae biofuels production
Tang et al. (1997) Cyanobacterial dominance of polar freshwater ecosystems
Hong et al. (2010) Axenic purification and cultivation of an Arctic cyanobacterium

Team:Amsterdam/Project/Applications

From 2011.igem.org