Team:UNITN-Trento/Project/Methyl Salicylate


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Results - Methyl Salicylate

It was difficult to find a volatile molecule that could be enzymatically produced by a bacterium and also demonstrated to be an efficient ripening inhbitor. There were not many candidates to choose from and after a long search we chose methyl salicylate (MeSA). Previous publications suggested that MeSA could inhibit the ripening of either kiwifruit and tomatoes, at a concentration of 0.5 mM (Ding, C. and Wang, Plant Science 2003, Y. 164 pp. 589-596.) (Aghdam M. et al., Journal of Agricultural Science. June 2011, Vol. 3, 2, pp. 149-156.)

Fortunately many of the needed parts were already available because of the work of the MIT iGEM 2006 team (Eau de Coli).

We modified and improved these parts and resubmitted them to the registry, as they were not available in pSB1C3.

MeSA detection

To have a quantitative analysis we used a Finnigan Trace GC ULTRA with a flame ionization detector (FID) that allowed us 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).

Figure 1: induced sample produces MeSA. A culture transformed with BBa_K1065102 was grown until O.D. 0.6 was reached. The culture was then splitted in 2 samples and one was induced with 5 mM arabinose. 2 mM salycilic acid was added to both samples. After 4 h the samples were connected to the Gas Chromatograph and a measure was taken. The chromatogram clearly shows how induced sample has a characteristic peak corresponding to methyl-salycilate.