Team:UNITN-Trento/Project/Methyl Salicylate
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- | <span class="tn-caption center"><b>Figure 4:</b> Left panel: calibration curve obtained with different concentrations of pure MeSA in ethanol. Right panel: Quantification of MeSA by GC-FID. NEB10&beta cells transformed with <a href="">BBa_K1065102<a> supplemented with salycilic acid produce around 0.4 mM of MeSA. Non transformed cells and non induced cells did not produce any MeSA. Cells induced with arabinose and not supplemented with salycilic acid did not show any significant MeSA concentration (data not shown)</span> | + | <span class="tn-caption center"><b>Figure 4:</b> Left panel: calibration curve obtained with different concentrations of pure MeSA in ethanol. Right panel: Quantification of MeSA by GC-FID. NEB10β cells transformed with <a href="">BBa_K1065102</a> supplemented with salycilic acid produce around 0.4 mM of MeSA. Non transformed cells and non induced cells did not produce any MeSA. Cells induced with arabinose and not supplemented with salycilic acid did not show any significant MeSA concentration (data not shown)</span> |
Revision as of 20:27, 30 September 2013
B. fruity needed also a fruit ripening ihnibitor. It was difficult to find a volatile molecule that could be enzymatically produced by a bacteria and also proofed to be an efficient ripening inhbitor. There were not many candidates to choose from and after a long search we found methyl salicylate (MeSA). Previous work suggested that MeSA inhibits the ripening of kiwifruit (Aghdam M. et al., Journal of Agricultural Science. June 2011, Vol. 3, 2, pp. 149-156) and tomatoes, at a concentration of 0.5 mM (Ding, C. and Wang, Plant Science 2003, Y. 164 pp. 589-596).
We were happy to find out that many of the needed parts to produce MeSA were already available in the registry. These parts were initally built by the MIT 2006 iGEM team for the project Eau de coli.
![](https://static.igem.org/mediawiki/2013/d/dd/Tn-2013_MeSA_path.jpg)
We modified and improved these parts and resubmitted them to the registry. For example, we substituted the pTet promoter controlling the BSMT1 enzyme with an araC-pBAD promoter. Additionally the MIT team did not include in their MeSA generator device the enzyme SAM synthetase, that we hope will boost MeSA production. We also have re-submitted in pSB1C3 the single enzymes of the pathway.
![](https://static.igem.org/mediawiki/2013/4/41/Tn-2013_Mesa_main_parts.jpg)
MeSA is an highly volatile liquid with a distinct minty fragrance. We exploited the physical properties of MeSA to quantify its production by gas chromatography using a Finnigan Trace GC ULTRA connected to a flame ionization detector (FID). This kind of instrument, is able to detect ions formed during MeSA combustion in a hydrogen flame. The generation of this ions is proportional to MeSA concentration in the sample stream. A calibration curve was initially created using samples with a well known pure MeSA concentration (0 mM, 0.2 mM, 0.5 mM, 1.0 mM, 2 mM).
NEB10β cells transformed with BBa_K1065102 were grown in M9 medium, induced with 5 mM arabinose and in some cases supplemented with salicylic acid. All the gas chromatography measures here reported were done in liquid phase, by injecting 1 ul of pre-filtered culture in the instrument.![](https://static.igem.org/mediawiki/2013/d/d4/Induced_sample_produce_MeSA.png)
![](https://static.igem.org/mediawiki/2013/4/4f/Tn-2013_Taratura_MeSA.jpg)
![](https://static.igem.org/mediawiki/2013/3/3f/Tn-2013_Istogramma_mesa.jpg)