Difference between revisions of "Team:Imperial College/Proof"

For our proof of concept we decided to use chromoproteins as a visual demonstration of co-culture systems for consolidated bioprocessing. Chromoproteins are obtained from anthozoans and, when expressed, give out bright colour visible to the naked eye. We wanted to use chromoproteins as a proof of concept that co-culture cells at different ratios can be used to make a products with varying compositions. In this case our products are colours of different shades and hues.

For our colour gene cosntructs, we went through the iGEM distribution kit and found coding sequences of different chromoproteins, seven of which we decided to use.
These are: spisPink, amajLime, amilGFP, fwYellow, eforRed, gfasPurple and cjBlue.

We assembled these coding sequences with an RBS part with a built-in Anderson promoter and a terminator. We next transformed these constructs into top ten cells for characterization.

We first mixed these coloured cells manually to demonstrate that different ratios of chromoproteins can produce different colours. These are demonstrated in the table below.

Figure 1: Picture of the different colours obtained by manually mixing different ratios of colored cells.

We also investigated the different growth rates of cells expressing different chromoproteins. This was done to show that the differences in metabolic burden imposed by the production of different proteins could affect the growth rate of the cells. This lead to instability of the co-culture.

Figure 2: Plot of Growth rate versus time for Escherichia coli Top 10 cells expressing various color constructs.

We picked a chromoprotein that does not effect growth as much as the others and ligated in our arabinose-inducible GP2 construct. This GP2 construct allowed us to control the growth of the coloured cells and provide a way to maintain a stable co-culture.

Figure 3: Plot of Growth rate versus time for the eforRed with growth control gp2 construct Escherichia coli Top 10 cells.