Heterocyst

Heterocyst:-

> Many filamentous members possess specia­lized cells of disputed function (supposed to be the centre of N2 fixation) known as heterocysts.

> Several cyanobacteria have the ability of nitrogen fixation. The filamentous forms possess special large pale cells or heterocyst’s for this. Some of the fixed nitrogen comes out as excretion. After death of cyanobacteria the substratum becomes rich in nitro­gen. Such nitrogen fixing cyanobacteria are now regularly inoculated in the rice fields. This saves consumption of nitrogen fertilizers.