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Team:Tokyo Tech/BlackenedEcoli
From 2009.igem.org
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Contents |
Summary
1, We confirmed Blackened E.coli by the melA gene.
2, Darkness of melA expressing cells are up 10 fold from control.
Introduction
One of the famous black pigment is a Melanin which was utilized in a number of organism. Previously. It’s noted that the body color of E.coli was changed from white to black by a large amount of Melanin. Melanin was made by the melA gene. The melA gene code for a Tyrosinase (EC 1.14.18.1). Tyrosinase catalyze the first step of Melanin production pathway to make Dopaquinone. After production of Dopaquinone, Melanin is generated by nonenzymatical chain reaction. So, Overexprssion of tyrosinase in E.coli cause a large amount of Melanin. We considered these mechanism enable us to control the Mars temperature, get the heat energy that help to grow bacteria and, protect DNA from UV on the mars surface. Because of Melanin has a high efficiency heat absorption and absorb Ultra Violet.
Purposes
Increase Mars temperature
Increase Reserving thermal energy
E.coli can get thermal energy, even if it is a little, by changing the body-color to black and uses the energy for its metabolism.
Protection from UV ray
UV strength on the Mars’ surface is weakened by initial energy supply. But it can be easily changed by the convection of the atmosphere. So, we think it significant to blacken E.coli, which can protect them from variable UV ray.
How to make darker colored E.coli
Constructed synthesized melA gene by GENEART.
Utilize Melanin production pathway
Melanin was made by Tyrosinase (EC 1.14.18.1). Tyrosinase catalyze the first step of Melanin production pathway to make Dopaquinone. After production of Dopaquinone, Melanin is generated by nonenzymatical chain reaction. So, Overexprssion of tyrosinase in E.coli cause a large amount of Melanin.
Materials and Methods
Bacterial strains and cultivation
Construction of melA expressing vector
melA expressing analysis
Analytical methods
According to Stefan-Boltzmann law, blackbody emit per surface in unit time is calculated as
σT4,
where T is the temperature of the black body and σ = 5.67 * 10 − 8(W / m2K4) is constant value. The total energy that comes from the sun is calculated as
S(1 − A)πr2,
where S = 597(W / m2) is the energy which actually reaches the mars from the sun, A is the albedo of the Mars and r = 3.3972 * 106(m) is the radius of the Mars. Albedo is a ratio at which a planet reflect the sun light. Regarding the Mars as blackbody, the radiative equilibrium temperature of the Mars is estimated as
T=
.
If we succeeded in decreasing the albedo by making the Mars black, the temperature will change as the graph shows. x axis is year and y axis is temperature.
We assume that the albedo decreases as
A = 0.15 * exp( − x).
If we could change the albedo from 0.15 to 0.05, the temperature of the Mars would increase by about 6 Celsius degree.
