Team:Imperial College London/Wetlab/Results/Cheminduction

Experiment:

Different concentrations of IPTG were added to a 96-well plate of e-coli Top 10 cells containing LacI-RFP genetic constructs. Here we measured the optical density of the cells over-time, for different concentrations of IPTG to monitor the effects in the culture. The IPTG growth curve results are plotted below:

Figure 1: Effects of [IPTG] on cell growth: Note that the high initial OD value results due to cultures having grown for 1 hour prior the start of the measuring phase.

Simply plotting the raw data does not give sufficient information about possible trends. Therefore, further analysis was performed where: 1. The blank absorbance level was estimated

Figure 2: Variation of the blank well data in monitoring absorbance A1, A2, B1, B2: 4 wells containing blank M9 media.
2. We can see from figure 1 that there is an exponential growth phase that lasts for about 3 hours, so in order to extract the trend in growth rate, the ln(Absorbance) data was plotted over these time points (See figures 3,4,5). 3. In order to extract the trend, a linear regression method was applied and the growth rates were calculated.

Figure 3: Log plots of the exponential growth phase for different IPTG concentrations

Figure 4: Log plots of the exponential growth phase for different IPTG concentrations

Figure 5: Log plots of the exponential growth phase for different IPTG concentrations