Why are cyanobacteria not bacteria?
Is it because they can be nitrogen fixers?
Cyanobacteria, also known as blue-green algae, are actually considered a type of bacteria despite their name. They are not classified as true algae because they lack a nucleus and other complex organelles that eukaryotic organisms, such as algae and plants, possess. Instead, cyanobacteria fall under the domain Bacteria and are characterized by their ability to carry out photosynthesis.
Regarding your second question, some cyanobacteria are indeed capable of nitrogen fixation. Nitrogen fixation is the process by which certain microorganisms convert atmospheric nitrogen gas (N2) into a biologically usable form, such as ammonia or nitrate. Cyanobacteria have specialized cells called heterocysts that enable them to perform nitrogen fixation. These heterocysts provide an anaerobic environment necessary for the enzyme complex to carry out the nitrogen fixation process.
In summary, cyanobacteria are indeed bacteria, but they possess unique characteristics - such as photosynthesis and the ability to fix nitrogen - that differentiate them from other bacteria.