Composite
Delay test

Part:BBa_K257021:Experience

Designed by: Romain Bodinier   Group: iGEM09_Paris   (2009-10-19)

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Applications of BBa_K257021

Measurement of BBa_K257021 delay

BBa_K257021 was grown overnight in LB medium with:
- Glucose 1 %
- nothing
- IPTG (0.2mg/ml)

Each of the 3 overnight cultures was then diluted to the 1/100 in each of the 3 conditions. Fluorescence and OD were assessed in a Tecan plate reader. PTPR-Fluo OD.JPGPTPR-Normalized Fluo OD.JPG

In the second graph, fluorescence was normalized by the mean Fluo/OD of all the conditions where mRFP1 is continuously expressed.

We observe a delay of ~10000sec between the beginning of the experiment and the changes in RFP expression.

Note that the delay is shorter for the LB + glucose -> LB + IPTG shift than for the LB + glucose -> LB shift.

Microscopy


PtetRFP trans.jpg
x1000 observation on white light of E. coli with the pLac-TetR::pTet-mRFP construction


PtetRFP fluo.jpg
x1000 observation after fluorescence excitation of E. coli with the pLac-TetR::pTet-mRFP construction


Ptet RFP Glucose trans1.jpg
x1000 observation on white light of E. coli with the pLac-TetR::pTet-mRFP construction in presence of 1% glucose


Ptet RFP Glucose fluo1.jpg
x1000 observation after fluorescence excitation of E. coli with the pLac-TetR::pTet-mRFP construction in presence of 1% glucose


Conclusion :
In presence of glucose pLac is repressed and then in absence of TetR the pTet promoter is turned on and activates the transcription of mRFP. Accordingly to the construction more bacteria are fluorescent in presence of glucose than in the control.

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