User:James Chappell/Inducible

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Fig.1.1:Growth of E.colicontaining the I7107 device at 37oC with varying concentrations of [IPTG]- The growth is measured at OD600 for 6 hours
Fig.1.2:Corrected [GFP] vs time for E.coli containing I7107 induced at varying concentrations of [IPTG], see below for explanation of corrected GFP

Fig.1.3:Transfer Funciton of Corrected [GFP] vs time for E.coli containing I7107 induced at varying concentrations of [IPTG], see below for explanation of corrected GFP
Figure 1.1 it can be seen that the growth rate of the E.coli containing the I7107. All samples appear to follow the same pattern of growth, with an initial lag phase followed by an exponential phase of growth. However, within the results there is clear variation. This variation is due firstly to the fact the overnight cultures added to media were not added in terms of cell population but rather a standard volume of overnight culture was added. Other variation is due to intrinsic E.coli variation and the nature of data collection (see below).

Figure 1.2 shows the corrected [GFP] vs time for different concentrations of [IPTG] inducer. Corrected [GFP] was calculated by normalising by the OD600, background removed by removing the uninduced fluorescence and finally the fluorescence was converted into [GFP] using a calibration curve. As it can be seen there is an initial [GFP] this is because there was no negative sample to remove the background fluorescence of the cell. As it can be seen all samples increase over time, with an initial lag phase which continues into a exponential phase and appears to be reaching steady-state towards the end of the sampling. When look at these results in context of a transfer function, figure 1.3, we see that we are in the upper threshold of response where our system is saturated to inducer. The transfer between the lower and upper threshold was not captured within this data and is clearly an area for future work.
There is a lot of variation within the data collected for both figure 1.1, 1.2 and 1.3. The reason is firstly because of the intrinsic variation of expression in E.coli. In addition this data was a combined effort of Imperial College London Synthetic Biology Course and was collected by a group of around 30 engineers and biologist. This combined data introduces experimental variation that will have contributed to the variation seen.