Autotrophic organisms refer to organisms that only use inorganic compounds as nutrients to survive and reproduce, that is, they do not need organic substances for their survival. Autotrophic organisms can be divided into chemoautotrophic organisms and photoautotrophic organisms.

Cyanobacteria, also known as blue-green algae or cyanobacteria, is a large single-celled prokaryote with a long evolutionary history, chlorophyll content and oxygen-producing photosynthesis. Cyanobacteria can use the energy in sunlight to synthesize carbohydrate organic matter from carbon dioxide and water. In other words, cyanobacteria can survive without organic matter, as long as there are inorganic substances containing carbon, nitrogen, oxygen, sulfur, phosphorus and other elements, water and sunlight.

So cyanobacteria are autotrophs. It is a light autotroph among autotrophs.