Cyanobacteria are special categories of bacteria that can perform photosynthesis.
They have chlorophyll and carry out oxygen-producing photosynthesis as much as plants and eukaryotic algae do.
They also contain pigments such as carotenoids and phycobilin.
As a group, these can range in size .
Examples of cyanobacteria: Nostoc, Oscillatoria, Spirulina, Microcystis, Anabaena.
The function of cyanobacteria:
The cyanobacteria are the largest and most diverse group of photosynthesis bacteria.
The structure and physiology of the heterocyst ensure that it will remain anaerobic, it is dedicated to nitrogen fixation.
Cyanobacteria are the major microbes that fix nitrogen in paddy fields. Heterocysts are specialized nitrogen-fixing cells formed during nitrogen starvation by some filamentous cyanobacteria.
Cyanobacteria are capable of considerable metabolic flexibility.
The chloroplast present in the plant cell is believed to have evolved from endosymbiosis of cyanobacteria.