Team:UNITN-Trento/Project/Ethylene
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<img style="box-shadow:none; margin-bottom:-1em;"src="https://static.igem.org/mediawiki/2013/f/f8/Tn-2013-project_ethylene-Eth_path.jpg" alt="Ethylene pathway" /> | <img style="box-shadow:none; margin-bottom:-1em;"src="https://static.igem.org/mediawiki/2013/f/f8/Tn-2013-project_ethylene-Eth_path.jpg" alt="Ethylene pathway" /> | ||
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We characterized this gene in two chassis: <i>E. coli</i> and <i>B. subtilis</i>, using different contstructs that we designed. | We characterized this gene in two chassis: <i>E. coli</i> and <i>B. subtilis</i>, using different contstructs that we designed. | ||
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<img src="https://static.igem.org/mediawiki/2013/9/9b/Tn-2013-project_ethylene-BBa_K1065000.jpg" alt="E. coli EFE parts"/><br/> | <img src="https://static.igem.org/mediawiki/2013/9/9b/Tn-2013-project_ethylene-BBa_K1065000.jpg" alt="E. coli EFE parts"/><br/> | ||
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<img src="https://static.igem.org/mediawiki/2013/8/85/Tn-2013-project_ethylene-BBa_K1065001.jpg"/> | <img src="https://static.igem.org/mediawiki/2013/8/85/Tn-2013-project_ethylene-BBa_K1065001.jpg"/> | ||
Revision as of 21:46, 18 September 2013
Results - Ethylene
EFE (Ethylene Forming Enzyme - 2-Oxoglutarate Oxygenase/Decarboxylase) is our keyplayer in triggering fruit ripening. It catalyzes ethylene synthesis from 2-Oxoglutarate, a TCA cycle intemediate molecule.
![Ethylene pathway](https://static.igem.org/mediawiki/2013/f/f8/Tn-2013-project_ethylene-Eth_path.jpg)
EFE in E. coli
![E. coli EFE parts](https://static.igem.org/mediawiki/2013/9/9b/Tn-2013-project_ethylene-BBa_K1065000.jpg)
In E. coli, EFE-catalyzed ethylene production was characterized using BBa_K1065001, which is a composed part with EFE under the control of an AraC-pBAD promoter.
1. Toxicity test
A toxicity test was performed inducing EFE expression with 5 mM arabinose. The growth curve was then compared to a non-induced sample.
![Toxicity test plot](https://static.igem.org/mediawiki/2013/6/6f/Tn-20130627-Efe_Toxicity_test-PLOT.png)
As expected, induced samples showed a decreased growth rate.
2. Ethylene detection
Ethylene production was detected using a Micro Gas Chromatograph (see the protocol page for the adopted methodology). The instrument was calibrated using two different air mixtures with well-defined quantities of each molecule (carbon dioxide, oxygen and ethylene).
![Ethylene chromatogram](https://static.igem.org/mediawiki/2013/c/cf/Tn-2013_EFE_chromatogram.jpg)
To quantify the amount of ethylene produced the peak integral was converted into ppm.
Sample | Ethylene detected |
---|---|
Not induced | 0 ± 15 ppm |
Induced V = 1.5 ml | 61 ± 15 ppm |
Induced V = 3 ml | 101 ± 15 ppm |
3. Kinetic assay for ethylene production
We performed a kinetic assay in order to analyze ethylene production over time (see the protocol page for the adopted method).
![kinetic_EFE_plot](https://static.igem.org/mediawiki/2013/0/00/Tn-2013_kinetic_EFE_plot-2.png)
Figure 3 shows that induction of the culture at O.D.600 equal to 0.8 a.u. caused a 2-fold increase in ethylene production.
EFE under the control of a Blue light circuit in E. coli
![e.coli_bluelight-EFE_parts](https://static.igem.org/mediawiki/2013/5/59/BluelightEFE.jpg)
To build our final system we placed EFE under the control of a photoinducible circuit. We assembled the photoinducible circuit exploiting many subparts from different teams (Uppsala2011 and Berkeley 2006). The construct includes an inverter that allows ethylene production only in presence of light.
Photoinduced ethylene production - kinetic assay
We performed a kinetic assay in order to analyze ethylene production over time using (BBa_K1065XXX). When the culture reached an OD of 0.7, it was placed in a hermetically closed vial and exposed to a blue light led (470 nm) while it was connected to the micro GC (see the protocol page for the adopted method).
![EFE-blue_light_plot](https://static.igem.org/mediawiki/2013/2/28/Blue_light_EFE_kinetic.png)
EFE in B. subtilis
![](https://static.igem.org/mediawiki/2013/8/85/Tn-2013-project_ethylene-BBa_K1065001.jpg)