Biochemistry Questions / Explore the concept of heterocysts in cyanobacteria, detailing their differentiation process and role in nitrogen fixation. How do heterocysts create a microoxic environment and facilitate the exchange of nutrients within the filamentous cyanobacteria?

Heterocysts play an important role in fixing nitrogen in filamentous cyanobacteria when low levels of fixed nitrogen are present in the environment.

Cells along a filamentous cyanobacteria are capable of differentiating into heterocysts at regular intervals, with fixed nitrogen diffusing along the length of the filament to neighbouring vegetative cells.

During the formation of a heterocyst, the cell wall thickens to allow oxygen to be excluded. The formation of a microoxic environment is important during nitrogen fixation – nitrogenase is inhibited by the presence of oxygen. Neighbouring vegetative cells provide sucrose to the heterocyst.