Subcellular structures of free-living cyanobacteria

Cyanobacteria are the inventors of oxygen-producing photosynthesis and transformed the atmosphere of our planet this way. They shared their secrets then (in a very unusual way) with a large group of organisms, which nowadays form the basis of life at least on the surface of our planet. (Deep down below it is another story…). a large and ancient group of photosynthetic bacteria with enormous importance in evolutionary history. They are responsible for oxygen formation on early earth and for the formation of higher photosynthetic organisms.

The pictures published here give you an insight into the internal structures of free-living cyanobacteria. They have been adapted from Image 2.1 from Christiaan van den Hoek, Hans Martin Jahns, David G. Mann (1993) Algen, 3. Edition, Georg Thieme Verlag Stuttgart, New York. The images show the nucleoid (red colour), carboxysomes (yellow colour), gas vesicles (dark yellow colour), the thylakoid membranes (green colour) with associated phycobiliproteids (blue colour), cyanophycin granules (similar to starch granules, white colour), the bacterial cell wall (brownish colour) and a slime capsule (grey colour). Bacterial ribosomes are given as very small black bodies. The scale in the first image is 200 nm long and has a diameter of 20 nm.

Cytology of cyanobacteria

In the following two pictures only the photosynthetically active components have been marked in colour: thylakoid membranes in green and phycobiliproteids in blue colour.