Some archaea (primitive bacteria), which, for example, live in a swamp or in a bog, can glow. This phenomenon is visible under the microscope.
To make them glow in our laboratory, we change them artificially. Afterwards they light up green or red or blue, just as we want!
Even the glass bottle, which contains them, starts to glow.
Methanogenic archaea, which also occur in alpine swamps, are characterized by autofluorescence, which can be observed in microscopes. Bacteria can be genetically engineered to produce fluorescent proteins (green, red, blue fluorescent protein), which can also be observed under a microscope or in a liquid culture.
Institute of Microbiology