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Overview Sensitivity Tuner --- Characterisation --- Modelling Colour Generators --- Carotenoids (Orange/Red) --- Melanin (Brown) --- Violacein (Purple/Green) The Future Safety

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Violacein Pigments

Characterisation

Proof of pigment production

Successful Pigment Production

We transformed Top10 with pPSX-Vio+. After three colour eventually appeared, as shown below. Interestingly, the pigment appears to remain within the bacteria, with little or no bleeding into the media. We took the violacein pigment bacteria (right plate in photo) out of the fridge to find that the purple colour had started to develop. They were therefore left at room temperature overnight. The colour appears to be within the bacteria, with little or no bleeding into the media. The control plate (left plate) is the untransformed TOP10 E. coli.

Left: control plate - untransformed TOP10 E. coli, Right: Top10 transformed with pPSX-Vio+.

Pigment production efficienty

The Vio operon is currently on a very low copy number plasmid; moving it onto a higher copy number plasmid may accelerate pigment production.

Left: Violacein growth on agar plate (overnight). Right: Single colonies.

Left: Lawn of green bacteria on agar plate (overnight), derived by removing one gene from the violacein cassette. Right: Green colonies on agar plate.

Characterisation of colour output

We characterised the violacein pigment by carrying out the acetone extraction protocol used for carotene. The results were normalised for OD and then plotted as a graph of absorption units against wavelength:

We also looked at absorbance at 584nm (the maximum absorbance for violacein):