Team:CIDEB-UANL Mexico/project aroma


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iGEM CIDEB 2014 - Project

Aroma Module

Since the beginning of iGEM project, the use of fluorescent reporters has been used in each one of the proposed projects in previous years, trying to test the theoretical presence of other proteins in E. coli. For our iGEM 2014 project, this module proposed to promote the usage of aroma reporters, instead of fluorescent ones.

How is the Aroma module composed?

This gene is composed by the following parts (see figure 1A): (1) a constitutive promoter, (2) a RNA thermometer, also called ribo-switch; used to regulate the WinterGreen-odor protein production through temperature, (3) a Wintergreen-odor enzyme generator, used to allow the production of methyl salicylate, induced by salicylic acid, and (4) a terminator. All of these parts are ligated by an 8-bp scar (TACTAGAG).


Figure 1. Aroma Module

Different to fluorescent reporters, this module was made in order to (in the future) perform as an aroma reporter and also to test the correct function of the bacteria, for its future usage as a new reporter and functional part (CDS). It is desired to use this part in the project to replace the red fluorescent protein (RFP) in the Capture module. But it was preferable to test it apart to demonstrate its effectiveness. Similarly, this piece is also helpful for Union module, because when performing the filtration by silica, WinterGreen can demonstrate the presence of bacteria in the beads. The team added the RNA thermometer for regulating the production of the aroma in the project. Another reason for selecting the RNA thermometer as a regulator was to continue the CIDEB UANL 2013 work with it.

How does it work?


Figure 2. Production of Wintergreen Odor

This module has a constitutive promoter which will be regulated by temperature with the use of the RNA thermometer. When adding salicylic acid to the bacteria in a 32° Celsius environment, the production of the WinterGreen protein will begin.

Parts of the module







In the specific case of our aroma module, it will help the bacteria to continuously transcribe the WinterGreen gene in order to allow the bacteria to continuously produce the aroma. This promoter has a length of 35bp.


A RNA thermometer, used for temperature post-transcriptional regulation (thermo sensor), and is designed to initiate transcription around 32°C.



Produces a transferase to convert salicylic acid into methyl salicylate ( WinterGreen odor). The wintergreen odor generator requires of 2mM of salicylic acid to produce methyl salicylate. BSMT1 (BBa_J45004), WinterGreen Odor Generator original name, was created by MIT 2006. This year, the team optimized the sequence for Escherichia coli. The new biobrick has a length of 1,074bp.



Part made of 6bp, responsible for transcription stop. The terminator stops the production of methyl salicylate.

Full Device:

These 4 genetic parts form the Aroma device of the project (see Figure 3). The full device's length is 1,251bp (including restriction sites).


Figure 3. Aroma Device

Other teams that use RNA thermometer and WinterGreen (BSMT1)

RNA thermometer

·            TUDelft 2008: Temperature-sensing bacteria that changescolor at different temperatures; as a temperature reporter system inlarge-scale fermentations, or as a temperature-inducible protein productionsystem.


Figure 4. RNA Thermometer circuit, excerpted from TUDelft 2008 team

·            VictoriaBC 2009: NAND logic gate using the ribo-key/ribo-lock system designed by Berkeley 2006 team , producing RFP except when the cells are grown in the presence of both arabinose and IPTG, also coupling fluorescent outputs with the ribo-thermometers made by TUDelft 2008 team.

·            iGEM_CIDEB 2013: Production of Vip3ca3, which acts as a pesticide protein, regulated by specific temperatures in order to avoid overproduction and it will show activity against target organisms Coleoptera and Lepidoptera.


Figure 5. Circuit from iGEM CIDEB UANL 2013 team

WinterGreen (BSMT1)

·            MIT 2006: This device produces methyl salicylate in the presence of salicylic acid. Methyl salicylate smells strongly of mint (wintergreen). Production of methyl salicylate was verified both by scent and by gas chromatography: E. coli with no WGD did not produce methyl salicylate when SA was added to the medium, while E. coli with the WGD did produce methyl salicylate when SA was added to the medium.


Figure 6. Wintergreen odor enzyme (BSMT1) generator circuit by MIT 2006


● Huang, H. (2006, August 30). Part:BBa_B1002. Retrieved August 30, 2014, from

● iGEM2006_Berkeley. (2006). Part:BBa_J23100. Retrieved August 30, 2014, from

● iGEM2006_MIT. (2006). Part:BBa_J45004. Retrieved August 30, 2014, from

● iGEM CIDEB Team. (2013). iGEM CIDEB UANL 2013. Retrieved on March 31th, 2014.

● iGEM08_TUDelft. (2008). Part:BBa_K115017. Retrieved August 30, 2014, from

● MIT IGEM Team. (2006). MIT 2006. Retrieved on March 31th, 2014, from:

● TUDelft iGEM Team. (2008). TUDelft 2008. Retrieved on March 31th, 2014, from:

● VictoriaBC. (2009). VictoriaBC 2009. Retrieved on March 31th, 2014, from:

● Zubieta, Chole et al. (2003). Structural Basis for Substrate Recognition in the Salicylic Acid Carboxyl Methyltransferase Family. Manuscript submitted for publication. Retrieved from

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