The picture above shows colonies of Escheria coli bacteria that have had the Fes enzyme, which allows the bacteria to extract free iron, removed.
The small red dots are unhealthy colonies of bacteria that are chronically short of iron.
The larger whitish blobs, however, are healthy colonies formed by bacteria which have had Fes replaced with an artificial protein, Syn-F4, that performs the same function.
This is the first reported instance of an engineered organism successfully producing an artificial protein. The research – by chemists at Princeton University – is expected to find applications in materials design, food science, biofuel production and medicine.