The colors are pigments used by photosynthetic bacteria to harness energy from light.
The panels are made by filling thin acrylic tanks with mud from a pond. Some nutrients like iron, cellulose and sulfur are added to the mud and then the panels are illuminated with artificial light; preferably incandescent light like metal halides. The bacteria, which are already present in the mud in low numbers, begin to reproduce. This set up is based on a Winogradsky column. The Ukranian microbiologist Sergei Winogradsky pioneered the study of microbial ecology by growing many different types of bacteria together in the same vessel in the lab.
