Part:BBa_K606035:Experience

Characterization

This construct was transformed into BL21 strains expressing the T7 polymerase under IPTG induction.

Fluorescence kinetics

The measurements have been carried out on a spectrophotometer, at 37°C under transient shaking. The experiment lasted 4h, we tested several colonies and several IPTG concentrations. The OD 600nm and the fluorescence of the GFP (exc: 470nm / meas:515 nm) was measured every 5 min, and the ratio of the two was calculated.

All values were normalized by substracting the fluorescence/OD value of the well with 0 mM IPTG at time 0. The values given are in arbitrary units.

Fig1: Growth curves for BL21 strain carrying the part

After 2 hrs of induction, we see a clear increase of the fluorescence proportional to the IPTG concentration (that is to say with the quantity of T7 polymerase induced in the cell). After 4 hrs, the expression of GFP under the pT7 is still not saturated

Fig2: Comparison of the Fluo/OD ratio for transcription

Here, we plot the ratio of induction of the T7 polymerase dependant construct for the different concentrations of IPTG at a given time (4 hrs), taking the well with 0 IPTG at time 0 as the reference.