Team:UCL/Science/Results/Sensor

Azo-Sensor

In order to create a BioBrick Azo-sensor, we decided to investigate whether we could repurpose the BBa_K239009 SpyGFP stress sensor submitted by UCL iGEM 2009. We hypothesised that the ‘stress’ caused by the presence of the toxic dyes could activate the GFP promoter and in turn cause result GFP fluorescence with the addition of Azo-dyes.


This assay was performed by growing cells in the presence of the dyes at different concenctrations, periodically taking samples and centrifuging to form a cell pellet. The supernatant was discarded and the pellet resuspended in TAE??? buffer. Then, 3 measurements of the GFP fluorescence of the samples were taken and plotted. The results of this assay are below.


Figure 1 - BBa_K239009 SpyGFP stress sensor could be repurposed as a Azo-sensor module in Acid Orange 7 (AO7) dye-contaminated waste waters. Graph showing that E.coli transformed with the BBa_K239009 SpyGFP stress sensor demonstrates GFP fluorescence after incubation in LB media contaminated with AO7 dye. Please note that fluorescence measurements are initially diminished due to the presence of the AO7 dye. However, the increased levels of fluorescence of BBa_K239009 inoculations in low levels of AO7 during the later recordings suggest that GFP expression could be activated through the SpyGFP promoter. Time is shown in hours after incubation. Error bars indicate SEM, n=3.




Although in a very subtle way, low concentrations of Acid Orange 7 seem to have an inducing effect on GFP production of cells transformed with BBa_K239009 SpyGFP sensor around 10 hours after inoculation. This data suggests that this part could potentially be repurposed for detection of dye contaminants in natural or industrial water environments, and further testing with other dyes and concentrations will be carried our.